I need help with as much as I can get done please and thank you

What are the measures of ∠a, ∠b, ∠c and ∠d? explain how to find each of the angle measure.

15/16 as a decimal rounded to the nearest hundredth

A3-dimensional figure has a square base and 4 lateral faces that meet at a point. explain the difference between the cross sections when a slice is made perpendicular to the base through the vertex, and when a slice is made perpendicular to the base and not through the vertex