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F1.math*3
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1.Tony and Brian have $370 altogether.If Tony gives $65 to Brian ,the amount of money they have will be the same.Find the original amount of money that Tony has.2.The difference between two position integers is 12.If their sum is 40,find the smaller number.3.The sum of the ages of Mr Lee and his son is 53.4 years... 顯示更多 1.Tony and Brian have $370 altogether.If Tony gives $65 to Brian ,the amount of money they have will be the same.Find the original amount of money that Tony has. 2.The difference between two position integers is 12.If their sum is 40,find the smaller number. 3.The sum of the ages of Mr Lee and his son is 53.4 years ago,the age of Mr Lee is4 times that of his son.Find the ages of them.
1. Tonyand Brian have $370 altogether. If Tony gives $65 to Brian ,the amount of moneythey have will be the same. Find the original amount of money that Tony has. Method 1: Let $x be the amount of money that Tony has. Then, the amount of money that Brian has = $(370 - x) x - 65 = (370 - x) + 65 x - 65 = 435 - x 2x = 500 x = 250 Hence, the amount of money that Tong has = $250 Method 2: Let $x and $y be the amounts that Tong and Brian have respectively. x + y = 370 ...... (1) x - 65 = y + 65 ...... (2) From (2): x - y = 130 ...... (3) (1) + (3) : 2x = 500 x = 250 Hence, the amount of money that Tong has = $250 ===== 2. Thedifference between two positive integers is 12.If their sum is 40, find the smaller number. Method 1: Let x be the smaller number. Then the greater number = x + 12 (x + 12) + x = 40 x + 12 + x = 40 2x = 28 x = 14 Hence, the smaller number = 14 Method 2: Let x and y be the smaller number and the greater number respectively. y - x = 12 ...... (1) y + x = 40 ...... (2) (2) - (1): 2x = 28 x = 14 Hence, the smaller number = 14 ====== 3. Thesum of the ages of Mr Lee and his son is 53. 4 years ago, the age of Mr Lee is 4 times that of his son. Find the ages of them. Method 1: Let y be the age of Mr Lee's son. Then, the age of Mr Lee = 53 - y (53 - y) - 4 = 4(y - 4) 49 - y = 4y - 16 5y = 65 y = 13 53 - y = 40 Hence, the age of Mr Lee is 40,and the age of his son is 13. Method 2: Let x and y be the ages of Mr Lee and his son respectively. x + y = 53 ...... (1) x - 4 = 4(y - 4) ...... (2) From (2): x - 4 = 4y - 16 x - 4y = -12 ...... (3) (1) - (3): 5y = 65 y = 13 Put y = 13 into (1): x + 13 = 53 x = 40 Hence, the age of Mr Lee is 40,and the age of his son is 13.
其他解答:5FAD1C75CFAE8A5F
F1.math*3
發問:
1.Tony and Brian have $370 altogether.If Tony gives $65 to Brian ,the amount of money they have will be the same.Find the original amount of money that Tony has.2.The difference between two position integers is 12.If their sum is 40,find the smaller number.3.The sum of the ages of Mr Lee and his son is 53.4 years... 顯示更多 1.Tony and Brian have $370 altogether.If Tony gives $65 to Brian ,the amount of money they have will be the same.Find the original amount of money that Tony has. 2.The difference between two position integers is 12.If their sum is 40,find the smaller number. 3.The sum of the ages of Mr Lee and his son is 53.4 years ago,the age of Mr Lee is4 times that of his son.Find the ages of them.
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最佳解答:1. Tonyand Brian have $370 altogether. If Tony gives $65 to Brian ,the amount of moneythey have will be the same. Find the original amount of money that Tony has. Method 1: Let $x be the amount of money that Tony has. Then, the amount of money that Brian has = $(370 - x) x - 65 = (370 - x) + 65 x - 65 = 435 - x 2x = 500 x = 250 Hence, the amount of money that Tong has = $250 Method 2: Let $x and $y be the amounts that Tong and Brian have respectively. x + y = 370 ...... (1) x - 65 = y + 65 ...... (2) From (2): x - y = 130 ...... (3) (1) + (3) : 2x = 500 x = 250 Hence, the amount of money that Tong has = $250 ===== 2. Thedifference between two positive integers is 12.If their sum is 40, find the smaller number. Method 1: Let x be the smaller number. Then the greater number = x + 12 (x + 12) + x = 40 x + 12 + x = 40 2x = 28 x = 14 Hence, the smaller number = 14 Method 2: Let x and y be the smaller number and the greater number respectively. y - x = 12 ...... (1) y + x = 40 ...... (2) (2) - (1): 2x = 28 x = 14 Hence, the smaller number = 14 ====== 3. Thesum of the ages of Mr Lee and his son is 53. 4 years ago, the age of Mr Lee is 4 times that of his son. Find the ages of them. Method 1: Let y be the age of Mr Lee's son. Then, the age of Mr Lee = 53 - y (53 - y) - 4 = 4(y - 4) 49 - y = 4y - 16 5y = 65 y = 13 53 - y = 40 Hence, the age of Mr Lee is 40,and the age of his son is 13. Method 2: Let x and y be the ages of Mr Lee and his son respectively. x + y = 53 ...... (1) x - 4 = 4(y - 4) ...... (2) From (2): x - 4 = 4y - 16 x - 4y = -12 ...... (3) (1) - (3): 5y = 65 y = 13 Put y = 13 into (1): x + 13 = 53 x = 40 Hence, the age of Mr Lee is 40,and the age of his son is 13.
其他解答:5FAD1C75CFAE8A5F
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