Question 166257
M=S+11
M+8=2(S+8)
(S+11)+8=2(S+8)
S+19=2S+16
S-2S=16-19
-S=-3
S=3 YEARS OLD FOR THE SISTER NOW.
M=3+11=14 YEARS OLD FOR MARK NOW.
PROOF:
14+8=2(3+8)
22=2*11
22=22