Question

The rectangle below has a total perimeter of 125 cm:

Picture of a rectangle with width of 5

Which of the following equations can be used to determine the length of the longer side of the rectangle?
A.) 2x + 10 = 125
B.) x + 5 = 125
C.) 5x = 125
D.) 25x = 125

Answer 1

A rectangle has four sides, two equal to the width and two equal to the length. So, the perimeter is

`p = 2w+2l`

If we know that the width is 5, and the perimeter is 125, we have

`125 = 2\cdot 5 + 2l \iff 125 = 10+2l`

In your case, the unkown is called x, but the concept is the same:

`2x+10 = 125`

where x is the length of the rectangle.