Answer:
x = 4
option C)
Explanation:
Triangle TSQ and QSR are congruent by considering HL congruency (Hypotenuse and leg of a right) which is that if hypotenuse SQ and one corresponding leg TQ and QR are equal in both triangles then both triangles are congruent.
so there corresponding angles will also be equal
2x + 13 = 21
2x = 21 - 13
2x = 8
x = 8/2
x = 4