We see that the area is 159 3/8 and the length is 18 3/4.
Because the area is the length*width, to find the width, we must divide the area by the length.
Think of it this way:
Divide l on both sides:
And w is what we're looking for.
So, divide 159 3/8 by 18 3/4.
You should get that the width is 8.5 feet :)