Answer:
Let's identify what we know and what we are looking for. To start off, the question states that there is a flat rate of 500. This is the y intercept, because you start off with 500. It also states that it charges a fee of 50 per hour, which is your slope. So what we have now is y=50x+500. We know that A is asking how much it will be for 20 hours. We simply plug 20 into x, so we do y=50(20)+500 which gives 1500. For C, we repeat the same step and just plug in 50.