Question

the perimeter is 24 inches. a poster is 3 times as long as it is wide. what are the length and width of the poster.

Answer 1

24=3x+3x+x+x add like terms
24=8x divide by 8
3÷x
plug I'm 3 for x
3×3=9 so length is 9
and width is 3

Answer 2

In this question the main information's are already provided. Based on them the answer to the question can be easily deduced.
Let us assume the width of the poster = x
Then the length of the rectangle = 3x
The perimeter of the rectangle = 24 inches
we already know
Perimeter = 2 ( Length + width)
24 = 2( 3x + x)
24 = 2 * 4x
24 = 8x
x = 24/8
  = 3
So the width of the rectangle is 3 inches
Length of the rectangle = 3x
                                     = 3 * 3
                                     = 9
So the length of the rectangle is 9 inches.