The width of a rectangle is 7 inches less than its length. The area of the rectangle is 120 square inches. Solve for the dimensions of the rectangle.

Question

I don't know how to put the equation together.

Answer 1

Hi, Davis.  

 

You can translate the first sentence into an equation by using "w" and "L" for width and length, respectively.  Note that the word "is" means an equals sign in "math language".  Also, the phrase "7 inches less" means "subtract 7 from".  Hence, the first sentence becomes:

 

w= L-7

 

To find the second equation, you need to know the formula for the area of a rectangle.  Area equals width times length.  That means the second equation is A = w(L).  

 

We know that the area is 120, and we also know that w= L-7.  That measn we can replace "A" with "120" and "w" with "L-7".  We get:

 

120 = (L-7)(L)

 

You'll need to multiply the two factors on the right hand side.  The resulting equation will be quadratic, which means factoring or using the quadratic formula.  

 

Hope that helps!

 

Alix