combine like terms on the left side. you always go from left to right.
The formula of an area of a square:

a - a side
We have 
substitute:

Used:

Answer:
Step-by-step explanation:
The length of the midsegment is half of the base in this case.
12x = 8x + 40
4x=40
x=10
So it's 60
Answer:

Step-by-step explanation:
- Assignment: Find area of rectangle without triangle
Area of whole rectangle including triangle: 66 Feet
(6 * 11 = 66)
Area of Triangle: 
Height: 3
Base: 6 (Solved by using this: (11 - 2 + 3))
Half of base: 3
3 * 3 = 9
66 - 9 = 57
3 (2x + 4y - y) Combine like terms (4y and -y)
3 (2x + 3y) Use the Distributive Property [(3 · 2x) + (3 · 3y)]
6x + 9y