Jock is 5 years older than sam , who is m years old. the sum of their ages is

2m+5

Steps:

Sam = m years old

Jock = (m+5) years old, because Jock is 5 years older than Sam

Sum of their ages means we add them up

m+(m+5) = m+m+5 = (m+m)+5 = 2m+5

good luck on your studies! : )

david edward.