20,000 people voted in each county, and there are 7 counties. What is the
order of magnitude for the total
number of people who voted?

(x - 1)( x - 2) (x + 2) = x³ -x² -4x + 4.

Explanation:

1) Given equation:

    3             5x            x + 2
- +  = 
 x + 2        x - 1       x² - 3x + 2

2) So, the denominators are x + 2, x - 1, and x² - 3x + 2

3) The LCD is the product of the common and non common factors raised to the greatest power.

4) x + 2, and x - 1 are already prime factors

5) Factor x² - 3x + 2

x² - 3x + 2 = (x - 2)(x - 1)

6) Then, the factors are x + 2, x - 1, and x - 2, and the LCD is the product of them:
(x - 1)( x - 2) (x + 2)

7) If you expand the products (distributive property) you get:
x³ -x² -4x + 4.