I need help don't understand

Given:

The number of ribbons it can sell each week, x, is related to the price p per ribbon by the equation:

To find:

The selling price if the company wants the weekly revenue to be $1,600.

Solution:

We know that the revenue is the product of quantity and price.

We need to find the value of p when the value of R is $1600.

Divide both sides by 100.

Splitting the middle term, we get

Using zero product property, we get

or

or

Therefore, the smaller value of p is $2 and the larger value of p is $8.