標題:
Equation
發問:
1. After 16 years,Kenneth will be 2 times as old as he was 12 years ago.Set up an equation for findinghis current age. 2.There are 42 students in S1A.The number of boys is 3/4 times taht of girls. Find the respective number of boys and girls there. 更新: taht=that!!!!!
最佳解答:
1. let y be kenneth's current age. y+16=(y-12) x 2 y+16=2y - 24 -y=-40 y=40 ::kenneth's current age is 40. 2. let y be the number of girls. y+y x 3/4=42 y+ 3y/4=42 4y+3y=168 7y=168 y=24 ::the number of girls is 24. the number of boys=42-24=18
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其他解答:
1)Let his current age be x. x+16=2×12 x+16=24 x+16-16=24-16 x= 8 ' His current age is 8. 2)Let the respective number of girls be x. Then let the respective number of boys be 3/4x. x+3/4x=42 x+3/4x÷3/4=42÷3/4 2x=48 x=12 'The respective number of girls is 24 The respective number of boy is 24×3/4 = 18 我也是用這本書的，這課已教完，你可放心
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