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.

Answer 1

R=3*S
in 6 years ⇒R+6=2*(S+6)
3*S+6=2*S+2*6
3S+6=2S+12
3S-2S=12-6
S=6 
R=3*6=18 ( Ralph 's age now)

in 6 years Ralph's age will be 3*x+6