Question

The perimeter of the rectangle shown below is 24 feet what’s the length of side d?

Answer 1

The complete question in the attached figure

we know that 
perimeter=24 ft
[the perimeter of a rectangle]=2*8+2*x-----------> 16+2x
24=16+2x-------> 2x=24-16----------> 2x=8----------> x=4 ft

the answer is
the option C) x=4 ft