SOLUTION: The legth of a rectangle is 1 less the 3 times its width. The permeter is 30. How do you findthe length?

Algebra ->  Rectangles -> SOLUTION: The legth of a rectangle is 1 less the 3 times its width. The permeter is 30. How do you findthe length?      Log On


   

Question 878505: The legth of a rectangle is 1 less the 3 times its width. The permeter is 30.
How do you findthe length?
Answer by erica65404(394) About Me  (Show Source):
You can put this solution on YOUR website!
The first step is to write equations for length and width.
Length is 1 less than 3 times width or length is 3 times width minus 1.
L=3W-1
L is length and W is width.
Width on the other hand is simply W=W.

Now the equation for the perimeter is P=2L+%2B+2W or P=+L%2BL%2BW%2BW. The first option is simpler.

Plug in 3W-1 for L then solve for W.

30=+2%283W-1%29%2B2W
30=6W-2%2B2W
32=8W
W=4

We are looking for length so we plug 4 back into length's equation.
L=3W-1
L=3%284%29-1
L=11

Check answer.
30=2%2811%29%2B2%284%29
30=30

The length is 11.