Question

The length of a rectangle is 3 inches less than its twice the width. If the perimeter is

78 inches, what is its width?

Answer 1

first lets write the formula for the perimeter of a rectangle: P = 2L + 2W or Perimeter = 2*Length + 2*Width

Now lets write the information that we know form the problem given:

We are told that the Perimeter = 30 inches

We are told that the Length is 3 inches less than twice its width. So lets rewrite this one into the equation. The length (L) is equal to (=) 3 inches less (-3) than twice its width (2W). Therefore, L = 2W-3

So now we have an equation to plug in for L and we still do not know what W is

Next, Plug into the equation!

P = 2L + 2W

30 = 2 (2W-3) +2W

Now Solve!

30 = 2 (2W-3) +2W

30 = 4W-6+2W

+6 +6

36 = 4W + 2W

36 = 6W

6 = W

Now we know what W is we can plug in to find L

P = 2L + 2W

30 = 2L + 2(6)

30 = 2L + 12

-12 -12

18 = 2L

9 = L

The length of the rectangle is 9 inches!

Explanation: