In this problem, the reference of the scale is referring to feet. Firstly, convert 72 inches to feet so that you can properly make the proportion.
72 inches = 6 feet
With the scale of 2 inches per 3 feet, we can set up an easy proportion to see how wide the door will be on the drawing.
3 feet 6 feet
——— = ————
2 inc. ‘x’ inc.
3x=12
X=4 inches
Solving the proportion by cross-multiplication reveals that the scale drawing of the patio door would be 4 inches wide.
