Question

Ralph is 3 times as old as Sara. In 6 years, Ralph will be only twice as old as Sara will be then. Find Ralph's age now.

Which of the following equations could be used to solve the problem?
x + 6 = 2(3 x + 6)
3 x + 6 = 2 x + 6
3 x + 2 x
3 x + 6 = 2( x + 6)

Answer 1

Answer: 3x+6 = 2(x+6)

Explanation:

Ralph's age: y; Sara's age: x

Ralph is 3 times as old as Sara: y = 3x

In 6 years, Ralph will be only twice as old as Sara will be then: (y+6) = 2(x+6)

Substitute y=3x into (y+6) = 2(x+6).

3x+6 = 2(x+6)