Question

​Parallelogram ABCD​ is a rectangle. AC=2y+7 BD=3y−4 What is the value of y?

Answer 1

You didn't attach an image so I will assume that AC and BD are opposite sides. In a parallelogram, opposite sides are congruent which means:

2y + 7 = 3y - 4

-y = -11

y = 11