Question 10815
Let R be Roz's present age and G be Grace's present age.

1) R = 2G

2) R+5 + G+5 = 28  Substitute R = 2G and solve for G.

2G+5 + G+5 = 28 Simplify and solve for G.
3G + 10 = 28 Subtract 10 from both sides.
3G = 18 Divide both sides by 3.
G = 6

R = 2G
R = 12

Roz is 12 years old.
Grace is 6 years old.