An electrician charges his customers an hourly rate plus a service fee of $30. The table shows the amount of money the electrician earned from his last four customers. What equation represents a customers charge, C, for x hours of service

OK, so first to find the cost per hour, we need to take the first listing on the table, 3 hours for $94.50. First, since there is a service fee of $30, subtract that. $94.50 - $30 = $64.50

Now this is the cost for 3 hours. So let's divide that to find out the cost per hour: $64.50/3 = $21.50

In this case, we now know that it cost $21.50 times x hours plus $30 for any customer. So the equation is C = 21.50x + 30