We have two similar triangles here, which means that all of their angles match up and are the same.
Q = T = 40
R = U = ?
S = V = 63
The measure of a triangles interior angles is 180 degrees.
40 + R + 63 = 180
103 + R = 180
R = 77
The measure of angle R is the first option, 77 degrees.
Hope this helps!! :)
