on 5)
recall that linear angles are angles that lie side by side on a flat-line, and add up to 180°.
the angle across the 78° then, is her sibling vertical angle, and therefore is 180 - 78 or 102°.
since all interior angles in a triangle add up to 180°, then a + 42 + 102 = 180, meaning a = 180 - 42 - 102, a = 36°.
about 6), check the picture below.
vertical angles, are just angles across each other at a junction, and are twins.
the angle 115°, has a twin across the junction, as you see in the picture, the 115° in red.
that vertical angle has a linear angle sibling of 65°, all interior angles in a triangle sum up to 180°, meaning the last angle in that bottom-right triangle is 85°, as you see there.
anyhow, as you see, we do the same thing with the triangle on the upper-right, and we get those linear angles of 99° and 95° there.
the sum of all interior angles in any polygon is 180(n - 2), n = sides, in this case, we have a quadrilateral on the bottom-left, and so those 4 angles must addd up to 180( 4 - 2), or 360°. That means e = 51°.
7) is cut off in the picture, so, but I noticed you posted it again.