Question

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

Explanation:

Step1: Find area of large rectangle

The large rectangle has length $l = 15$ feet and height $h=21$ feet. The area of a rectangle is $A = l\times h$. So, $A_{1}=15\times21 = 315$ square - feet.

Step2: Find area of small rectangle

The small rectangle has length $l = 8$ feet and height $h = 7$ feet. The area of a rectangle is $A = l\times h$. So, $A_{2}=8\times7=56$ square - feet.

Step3: Find 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. $A = A_{1}-A_{2}=315 - 56=259$ square feet.

Answer:

259 square feet