# My name is Gabriel and I need help with this SAT problem.

• May 13th 2013, 01:38 PM
pieRsquared
My name is Gabriel and I need help with this SAT problem.
The length of a rectangle is increased by 20%, and the width of the rectangle is increased by 30%.

By what percentage will the area of the rectangle be increased.
a)25%
b)36%
c)50%
d)56%
e)60%

I already know the answer, all I want is a detailed explanation and steps for solving this.

Thank you!
• May 13th 2013, 01:48 PM
emakarov
Re: My name is Gabriel and I need help with this SAT problem.
By not giving the values of the lengths x and y of the rectangle's sides, the question seems to imply that the answer does not depend on them. So, take some concrete x and y (e.g., x = y = 10) and calculate. Then it would be nice to show that the same answer holds for any x and y.
• May 13th 2013, 01:53 PM
Plato
Re: My name is Gabriel and I need help with this SAT problem.
Quote:

Originally Posted by pieRsquared
The length of a rectangle is increased by 20%, and the width of the rectangle is increased by 30%.
By what percentage will the area of the rectangle be increased.
a)25%
b)36%
c)50%
d)56%
e)60%
I already know the answer, all I want is a detailed explanation and steps for solving this

If the original area is $\displaystyle A=\ell\cdot w$ then the new area is $\displaystyle A'=(1.2\ell)\cdot(1.3w)$.

What is $\displaystyle A'-A=~?$