Ican't seem to find the answer for number 2 can someone at least give me a hint?

Me write an equation for the interior angles of this triangle that uses the triangle sum theorem

Adj has a total of 1075 dance and rock songs on her system. the dance selection is 4 times the size of the rock selection. write a system of equations to represent the situation.

Aball is dropped from a height of 10m above the ground. it bounce to 90% of its previous height on each bounce. what is the approximate height that the ball bounce to the fourth bounce?