Question 575561
The length of a rectangle is 5 meters longer than the width. The area is 300 square meters. How long is the rectangle? 
sol:
let the unknown parameter width be x
and length = 5 + x , as given
area = 500 sq units
l * width = area
so subtitute what you know in the above equation 
(5 + x)*(x) = 300------------- 1
the above equation is the required one to find the length.
solve for x which gives length = 15 meter