Answer:
780ft²
Step-by-step explanation:
I'd cut that lower part off into a separate section, and then its width would be the difference of 40 and 30, and its height the difference of 24 and 18. Then, with just 2 rectangles, you can easily calculate the area of each and add them up.
[tex]40-30=10\\24-18=6[/tex]
The lower rectangle is 10' × 6'.
Upper rectangle:
[tex]40\times18=720[/tex]
Lower rectangle
[tex]10\times6=60[/tex]
Add them up:
[tex]720+60=780[/tex]
780ft²
