Hey there!
First, we must identify that our unknown is the brother's - and we must create an equation since it says "equals to".
If we assign b to brother's age, we have:
14 (sister's age) is equal to: b - 12 (brother's age minus 12)
=
14 = b-12
Add 12 to both sides:
26 = b
To check:
14 = 26-12
14 = 14
Therefore, the brother is 26.
Hope this helps!
