Answer:
x = 55
Step-by-step explanation:
In a rhombus, each diagonal bisects a pair of opposite angles.
For this parallelogram t be a rhombus, the angles with measures 2x - 40 and x + 15 must be congruent.
2x - 40 = x + 15
Subtract x from both sides.
x - 40 = 15
Add 40 to both sides.
x = 55
