Question 422332
"John is twenty years younger than Amy, and in five years' time he will be half her age. What is John's age now?"


x = Amy's age now
x - 20 = John's age now


x + 5 = Amy's age in 5 years
x - 15 = John's age in 5 years


x - 15 = 1/2(x + 5) {in five years, he will be half her age}
2x - 30 = x + 5 {multiplied entire equation by 2 to clear fraction}
2x = x + 35 {added 30 to both sides}
x = 35 {subtracted x from both sides}
x - 20 = 15 {substituted 35, in for x, into x - 20}


Amy is 35 now
John is 15 now
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