how do i find the measure of R or whatever big confushion help

Answer:
m∠R= 87°
Step-by-step explanation:
The angles in a polygon add up to (n-2)180
(5-2)180= 540°
You can set up an equation to add all the angles together equaling 540°.
Once you solve for x, plug that back into the formula for the angle of R(7x-11)