Question

In order for the parallelogram to be a rhombus, x = [?]. (5x + 25) (12x + 11)

Answer 1

A parallelogram is also a rhombus if the diagonal is a bisector of an angle enclosed by the two adjacent sides of a parallelogram.

In our case it means,

$5x+25=12x+11$

$7x=14\implies x=\boxed{2}$

Hope this helps.