suggesting that revenue will be zero for a charge of 0 or for a charge of 12, and that fixed expenses are 4700. Charges less than 0 are uninteresting, and charges high enough to cause the number of customers to be negative also don't make any sense in this context.
Though out of the range of likely consideration, charges low or high enough to cause profit to be negative (more than 9.54, for example) seemingly can be reasonably modeled by this function.
you multiply it as you would regular numbers and then you count the places that the decimal is in front of. in this case it would be 2 numbers, then in the number you got by multiplying, move the decimal 2 places up