Question

Parallelogram ABCD is a rectangle.

Answer 1

we know that

If the parallelogram ABCD is a rectangle

then

$BD=AC\\AC=AX+XC\\AX=XC$

so

$2AX=BD$ ------> equation A

Substitute the given values in the equation A

$2(3y-5)=5y$

Solve for y

$6y-10=5y$

$6y-5y=10$

$y=10$

therefore

the answer is

$y=10$ units

Answer 2

You must set the equations equal to each other.
Meaning, 3y - 5 = 5y
divide both sides by -3y, you'll get -5/2.

Then make an equation:
2ax = bd
2(3y-5) = 5y
6y − 10 = 5y

Subtract 5y from both sides.
y − 10 =0

Add 10 to both sides.

y = 10