area of a rectangle= length*width
if the length is 3 1/2 ft and the are is 8 3/4ft...
(width=x)
the equation would look like...
8 3/4=3 1/2*x
you then divide 3 1/2 on both sides to leave x alone...
2.5=x
the width then turns out to be 2.5 ft
(if i helped out leave a thanks and a rate) c: