Ratio word problem

Question

betty is 12 years old. salina is 4 times as old as betty. in how many years time will salina be 3 times as old as betty ?

Answer 1

in 6 years Salina will be 3 times Betty's age

they're 12 and 48 now

in 6 years they'll be 18 and 54. 54=3(18)

48+x = 3(12+x) = 36 + 3x

2x = 48-36

x=12/2 = 6 years from now