Given the diagram above . .
1. is m∠a = 105? explain.
2. is ∠b = 75? explain.

1. Angle A is not 105degrees. As you can see on the horizontal line that it lies on, it's under 90degrees(acute). The angle aside from it is over 90degrees(obtuse).

2.Angle B is in fact not 75degrees.. By looking at the angle it's obtuse, over 90 degrees, so it can't be 75degrees.