A rectangle with a perimeter of 40 inches has a width that is 3 times the length. What is the length?

Divide by 4, the width is 10 inches, times by 3, the length is 30 inches

To find the perimeter of a rectangle, the formula is 2*length+2*width=perimeter.

So, say that the variable x is the length. Because the width is 3 times the length x, the width is equal to 3x.

I can plug what we know into the formula.

(2*x) + (2*3x) = 40

2x + 6x = 40

8x = 40

Divide both sides by 8 to get x = 5.

So, your length is 5 inches!

(To double check, you can just plug it into the problem. (2*5) + (2*15) = 10 + 30 = 40.)