just a quick rundown on 7), since the reply above is fine.
75°, a°, 70°, are all siblings of a flat-line, and therefore, are all linear angles, so 75 + a + 70 = 180, which means a = 180 - 75 - 70, a = 35°.
so that means the triangle with "b" and "a", has the angles of 95°, 35° and b, so clearly b = 180 - 95 - 35, b = 50°.
"c" has a linear angle sibling of 95°, meaning c = 180 - 95, c = 85°.
the angle with "c" and "d" has then the angles of 70°, 85° and d, which makes d = 180 - 70 - 85, d = 25°.