Tutors have the ability to create educational resources and share them with the WyzAnt community.
Here are some of the resources created by Oren.
View all of Oren’s resources

The trick to solving this problem is realizing that you need to break it up into parts. Find the number of totals with one, two, three, or four bills, then add them up. Since this is a combination problem, you can find each of the numbers with the combination
formula, but the numbers...

10.5 is equal to the fraction 21/2, so you can multiply 1.79 by two and divide by 21.

As has been noted above, the problem can be solved both factoring and the quadratic formula. If you can't factor or remember the formula, you can also solve it using a process called completing the square.
First, divide the equation through by a, and subtract c from both sides...