In parallelogram ABCD, the measure of angle A = 3x and the measure of angle B = x + 10.

Explanation:

See attachment for diagram

Given

Required

What is the measure of angle D?  ------ Missing part of the question

From the attachment, we have that

A is adjacent to B

And adjacent angles of a parallelogram add up to 180.

i.e.

Substitute values for A and B

Collect Like Terms

Solve for x

Also from the attachment,

D is at opposite of B

And opposite angles of a parallelogram are equal

i.e.

Substitute 42.5 for x