Answer: B. 55
Explanation:
You need to know that within one parallelogram, the same-side interior angles are supplementary angles, meaning that they add up to 180°.
---------------------------------------------------------------------------------------
Given
(2x+15)+x=180
Expand parenthesis
2x+15+x=180
Combine like terms
3x+15=180
Subtract 15 on both sides
3x+15-15=180-15
3x=165
Divide 3 on both sides
3x/3=165/3
x=55
Hope this helps!! :)
Please let me know if you have any questions