The area of a rectangle is Length times width.
You are given the width and area. To find the length you would divide the area by the width:
Length = 21/50 divided by 3/5
To divide fractions, flip the second fraction over and multiply:
21/50 x 5/3 = 21*5 / 50*3 = 105 / 150 , both numbers can be reduced by dividing each one by 15.
105/150 reduces to 7/10
The length of the rectangle = 7/10 mile
