Answer:
63.2 = y
Step-by-step explanation:
The perimeter is the sum of all the sides
P = 7.8+ y+37.6 + y
171.8 = 7.8+ y+37.6 + y
Combine like terms
171.8 = 45.4 + 2y
Subtract 45.4 from both sides
171.8-45.4 = 45.4 + 2y -45.4
126.4 = 2y
Divide each side by 2
126.4/2 = 2y/2
63.2 = y
