Answer:
Step-by-step explanation:
Call the angle immediately CCW from B (below line l2) angle C. Then angle C is corresponding with the one marked 55°, so is 55°. Angle B+C is supplementary to the one marked 75°, so is 105° Then ...
angle B = (B+C) - C = 105°-55° = 50°
Angle A is an alternate exterior angle to angle (B+C), so is congruent to it. That means ...
angle A = angle (B+C) = 105°
