First of all you have to find the missing measurements. The actual measurements for the angles in the hexagon are not given, but they give you an expression. You have to solve for x first so that you can plug it in and find the angle measurement. You have to equal the two sides that are given to you like this: 20x+48=33x+9. You solve for x and then plug it into each angle measurement. This should give you 108. Since it is a regular hexagon all of the sides are equal. If you look at the angle at the top of the hexagon you'll see two triangles and the angle. Since it lies on a straight line, it is all equal to 180. You already have the angle measurement of the hexagon and are missing the triangles. So 180-108=72. 72 is the missing part of the angle. You divide this by 2 in order to find each triangle angle measurements. the answer is 36 degrees.
<u>Part 1) which angle is congruent to Angle 1?</u>
we know that
When two lines are crossed by another line (which is called the Transversal), the angles in matching corners are called <u>corresponding angles</u>
m∠5=m∠1 ----------> by corresponding angles postulate
therefore
<u>the answer Part 1) is </u>
Angle 
Part 2) Which can be used to directly prove that Angle 1 =~ Angle 8?
we know that
<u>Alternate exterior angles</u> are defined as two exterior angles on opposite sides of a transversal which lie on different parallel lines.
in this problem
m∠1=m∠8 -------> by alternate exterior angles theorem
therefore
<u>the answer part 2) is the option </u>
Alternate Exterior Angles Theorem
<u>Part 3) If m Angle 5 = 42 degrees, what is m Angle 4?</u>
we know that
<u> Alternate interior angles</u> are two interior angles which lie on different parallel lines and on opposite sides of a transversal
m∠4=m∠5 --------> by alternate interior angles theorem
so
m∠4=
therefore
<u>the answer Part 3) is</u>

A = {1, 2, 5, 6, 8}
{1} U {2, 5, 6, 8}
{2} U {1, 5, 6, 8}
{5} U {1, 2, 6, 8}
{6} U {1, 2, 5, 8}
{8} U {1, 2, 5, 6}
{1, 2} U {5, 6, 8}
{1, 5} U {2, 6, 8}
{1, 6} U {2, 5, 8}
{1, 8} U {2, 5, 6}
{1, 2, 5} U {6, 8}
{1, 2, 6} U {5, 8}
{1, 2, 8} U {5, 6}
{1, 5, 6} U {2, 8}
{1, 5, 8} U {2, 6}
{1, 6, 8} U {2, 5}
The answer is 15 distinct pairs of disjoint non-empty subsets.