Question

how many square feet of drywall are needed for the wall shown in the figure to the right? for the given wall, 78.5 square feet of drywall is needed

Explanation:

Step1: Calculate area of large rectangle

The large rectangle has length $l = 14$ feet and width $w=12$ feet. The area of a rectangle is $A = l\times w$. So, $A_1=14\times12 = 168$ square - feet.

Step2: Calculate area of small rectangle

The small rectangle has length $l = 7$ feet and width $w = 5$ feet. The area of a rectangle is $A = l\times w$. So, $A_2=7\times5 = 35$ square - feet.

Step3: Calculate area of the wall

The area of the wall (the area of dry - wall needed) is the area of the large rectangle minus the area of the small rectangle. $A = A_1 - A_2=168 - 35=133$ square - feet.

Answer:

133 square feet