Question

Ralph is 3 times as old as Sara. In 6 years, Ralph will be only twice as old as Sara will be then.

Answer 1

R = 3S

R + 6 = 2 (S+6)

Substitute the first equation in the second one:

(3S) + 6 = 2 (S + 6)

3S + 6 = 2S + 12

S + 6 = 12

R = 18
S = 6

Check:

R is 3 times S now.

In 6 years, R will be (18 + 6) = 24, S will be (6 + 6) = 12.

24 = 2 x 12        yay