What does the Angle X =​

45 degrees

explanation: if x is in a square with all right angles that is 90 degrees and the entire square is divided in half it would be 45 degrees with the other corresponding angle 45 degrees minus 90 it is also 45 degrees

on friday there were 15 birds

the entire expression should be subtracted from 30. to subtract the quantity, distribute the negative sign, which changes the signs on the terms. so, the –2 changes to positive and gets added to 30 instead of subtracted from it.

hope this ! ^w^