Answer:
It decreases from 45° to 40°
Step-by-step explanation:
The secant angle GBJ is half the difference of the measure of its intercepted arcs, that is
∠ B = [tex]\frac{1}{2}[/tex] (CDF - GHJ) = [tex]\frac{1}{2}[/tex](130 - 40)° = [tex]\frac{1}{2}[/tex] × 90° = 45°
If arc GHJ is now 50°, then
∠ B = [tex]\frac{1}{2}[/tex](130 - 50)° = [tex]\frac{1}{2}[/tex] × 80° = 40°
That is ∠ B decreases from 45° to 40°
