12.
Let's set up an equation using w to represent the weekly allowance.
w/2 + 10 = 18
Then solve:
Subtract 10 from both sides
w/2 = 8
Multiply by two on both sides
w = 16
The answer is 16.
13.
Let's set up another equation using c to represent the original number of candy.
(c - 3) ÷ 5 = 3
Solve:
Multiply by 5 on both sides
c - 3 = 15
Add three on both sides
c = 18
The answer is 18
Hope this helped! If you have any more questions or don't understand, please comment or DM me. :)