Angle D is equal to Angle B because AB and DE are parallel to each other.
AD is a straight line so the (2) 2x angles and 72 degrees need to equal 180.
Setting up the equation you have:
2x + 2x + 72 = 180
Simplify:
4x + 72 = 180
Subtract 72 from each side:
4x = 108
Divide both sides by 4:
x = 108 / 4
x = 27
The answer is C; 35.5 units^2
a. The first variable is x and the second variable is y.
b. The equations are
and 
Step-by-step explanation:
Step 1:
The first step is to define the variables. The variables can be any two symbols, letters, characters, etc.
Here let the first variable be x and the let the second variable be y.
So the variables are defined as x and y.
Step 2:
The sum of the given variables is 12.
The first variable + the second variable = 12,

The difference between the two variables is 4.
The first variable - the second variable = 4.

Step 3:
If we add both the equations we get,
and 
x = 8 and y = 4.