Question

Mavis is 5 years older than her brother. Five years ago she was 2 times older than her brother. How old is each now?

Answer 1

15 and 10 because

five years ago he would be 10 and the brother would be 5 and 10 is double 5

Answer 2

M=Mavis
B=Brother Age
M=B+5

Five years ago...
M-5
B-5
Since Mavis is twice her brother age you have to multiple by 2
(M-5) = 2(B-5)

Substitute M=B+5
(B+5-5) =2B-10

B=2B-10

-B=10
10+5=15

Mavis is 15
Brother is 10