Check the picture below tell me if you understand what I did.
Answer:
15/2 or 7.5
Step-by-step explanation:

distribute 5/6 to each number

change the fraction 10/3 so that it will have the same denominator as 5/12
= 40/12

divide both sides by 5/6


" the sum " means add
(c + d) - 3 <== ur expression
91.5 is the perimeter. It's just 5a.