5) So for parallelogram ABCD, ∠B ≅ ∠D, and ∠A ≅ ∠C. Further, ∠B and ∠A are supplementary (i.e., their sum is 180°), and ∠D and ∠C are also supplementary.
So, we have that m∠B = m∠D. Therefore,

Now, let's substitute for x back into the expression for either ∠B or ∠D to find it's angle measure.
m∠B =

Now, remember that ∠B or ∠D are supplements of ∠A.
So, m∠B + m∠A = 180°.
That means m∠A = 180° – 72° = 108°.
That seems reasonable, because A appears to be an obtuse angle.
Answer: 18
Step-by-step explanation:
2(9)=18
Pretty sure it’s b, good luck
Explanation
Problem #2
We must find the solution to the following system of inequalities:

(1) We solve for y the first inequality:

Now, we multiply both sides of the inequality by (-1), this changes the signs on both sides and inverts the inequality symbol:

The solution to this inequality is the set of all the points (x, y) over the line:

This line has:
• slope m = 3/2,
,
• y-intercept b = -2.
(2) We solve for y the second inequality:

The solution to this inequality is the set of all the points (x, y) below the line:

This line has:
• slope m = -1/3,
,
• y-intercept b = 2.
(3) Plotting the lines of points (1) and (2), and painting the region:
• over the line from point (1),
,
• and below the line from point (2),
we get the following graph:
Answer
The points that satisfy both inequalities are given by the intersection of the blue and red regions: