Answer:
A = 20
Step-by-step explanation:
A + 71x - 1 = 90o That's because all triangles have 180 degrees.
71x - 1 + 20x = 90 Combine like terms.
91x - 1 = 90 Add 1 to both sides.
91x - 1 + 1 = 90 + 1 Combine
91x = 91 Divide by 91
91x/91 = 91/91
x = 1
Angle A = 20x
Angle A = 20*1
Angle A = 20
