Answer:
Option D. 50 ft
Step-by-step explanation:
we know that
The area of the figure is equal to the area of three rectangles
so
[tex]A=18x+(48-36)(32-11)+(18)(32)[/tex]
[tex]A=18x+(12)(21)+(18)(32)\\A=18x+828[/tex]
Remember that the area is given
[tex]A= 1,728\ ft^2[/tex]
so
[tex]18x+828=1,728[/tex]
solve for x
[tex]18x=1,728-828\\18x=900\\x=50\ ft[/tex]
