Ralph is 3 times as old as sarah. in 6 years, ralph will be only twice as old as sarah will be then. find ralph's age now. if x represents sarah's age now, which of the following expressions represents ralph's age in six years?

X - Sarah's age now
3x - Ralph is 3 times as old as Sarah, now
x+6 - Sarah's age in 6 years
2(x+6)=2x+12 - Ralph will be only twice as old as Sarah will be in 6 years
Ralph's age in six year can be also written as 3x+6

So
Ralph's age now is 3x.
Ralph's age in six years is 2x+12 and 3x+6.

We can find age of Sara now,
2x+12=3x+6
3x-2x=12-6
x=6,
Ralph's age now is 3x=3*6=18
Now Sara is 6 years old, Ralph is 18 years old.