Help please, I can’t get these down

Answer:
y = 15
Step-by-step explanation:
Opposite sides of a parallelogram are the same length. This means ...
5y -20 = 2y +25
3y = 45 . . . . . . . . . add 20-2y to both sides
y = 15 . . . . . . . . . . .divide by 3