Math
posted by Sally on .
A rectangular parking lot is 25 ft. ny 50 ft is increased on all 4 sides by the same amount. The area increased by 400 sq ft. What are the new dimensions of the parking lot?

(25+L)(50+L)=25*50+400
25*50+75L+L^2=25*50+400
L^2+75L400=0
l=(75+sqrt(75^2+1600))/2=(75+85)/2=
= 5
new dimensions: 30*55