Question

5. Mark's brother is five years older than Mark.

Their combined ages add up to 23. How old is
Mark?

Answer 1

9

Explanation:

Let's say Mark is M and his brother is B.

M+5=B

M+B=23

Now we can solve using subsitution.

M+M+5=23

(Subtract 5 from both sides)

2M=18

M=9

Hope this helped!