Find the measure of angle
b

75°

Step-by-step explanation:

since they are across from one another that means they will be the same

since 75 is across from b = that means b will be 75

∠acb = 8°

step-by-step explanation:

∠xba lies on the circle and is half the measure of the intercepted arc ax

hence

measure of arc ax = 2 × 42° = 84°

∠acb is outside the circle and is

∠acb = (arcab - arcax ), hence

∠acb = 0.5 (100 - 84) = 0.5 × 16° = 8°