Question 368933
Need to make 2 equations.
 
G=8+S
G+S=24     Substitute G=8+S into second equation.

G+S=24
(8+S)+S=24       Solve for S.
8+2S=24
2S=16
S=8  So we know that Sam is 8 yrs old.  Substitute S back into the first equation.

G=8+S
G=8+8
G=16  So Grace is 16 yrs old.