Nathaniel is going to use a computer at an internet cafe. The cafe charges an initial fee to use the computer and then an additional price per minute of usage. It is known that the total charge to use a computer for 5 minutes would be $9 and that the additional rate per minute of use is $0.20. Write an equation for the function C(t), representing the total cost of using a computer for tt minutes at the internet cafe.

If we know that we have a charge per minute it would look like mx with m being the charge for every x (minutes being used). We also know that there is an initial charge that has to be added on, but it won't change after the charge is set so we can call this "i".

Your equation from what we already know is going to be mx + i =Total charge.

Now that we have an equation, we an plug in what we know to solve for our initial charge. We plug in 0.2 for 5 since that is the cost for minute along with 5 for x since that is the amount of minutes. We do not know the initial charge so leave that as i, and plug 9 in for Total charge.

Your new equation should look like 0.2(5) + i=9 where we can multiply .2 by 5 and get 1 and then subtract 1 from both sides. This leaves you with 8=Total charge.

Since the problem is asking for a function representing the total cost we know that it is now C(t) 0.2x +8