The rectangular poster shown measures 2w-30 by w. The poster has an area of 5400 cm2. What is the value of w?

1. To solve this problem, you must use the formula of the area of a rectangle, which is shown below:

A=lxw

"A" is the area of the rectangle (A=5400 cm²).

"l" is the lenght of the rectangle (l = 2w-30).

"w" is the width of the rectangle.

2. When you substitute l=2w-30 into the formula A=lxw, you have:

A=lxw

5400 = (2w-30) (w)

5400=2w²-30w

2w²-30w-5400=0

3. Now you have a quadratic equation. When you solve it, you obtain the value of "w". Then:

w=60 cm