Question 129946
Erin's age is three times Warren's age. This can be expressed as:
E = 3*W
In four years, she (Erin) wil be twice as old as he (Warren) will be.  This can be expressed as:
E+4 = 2(W+4) Substitute the E = 3*W from the first equation and solve for W.
3*W+4 = 2(W+4) Simplify and solve for W.
3W+4 = 2W+8 Subtract 2W from both sides.
W+4 = 8 Subtract 4 from both sides.
W = 4
Warren's present age is 4 years.
Erin's present age is 3*W = 3(4) = 12 years.