Answer:
B = 56
Step-by-step explanation:
A + B = 90 degrees
(6x - 8) + (5x + 21) = 90
6x - 8 + 5x + 21 = 90
(6x + 5x) + (-8 + 21) = 90
11x + 13 = 90
11x + 13 - 13 = 90 - 13
11x = 77
11x/11 = 77/11
x = 7
Plug into (5x + 21).
5(7) + 21 =
35 + 21 = 56
B = 56
