Jeff wants to rent a boat. He has to pay a fixed base cost plus a daily rate for renting the boat. The table shows the amount of money, y, in dollars, that Jeff has to pay for renting the boat for x days:

Question

mathstudent55 · Answer

Let us think this through.

The cost of the boat rental is y.

y = a daily cost + a fixed cost

mathstudent55 · Answer

Notice what happens on day zero.
Even if he rents the boat for no days, it is already $3.
That means $3 does not depend on the number of days.
$3 is the fixed cost.
We now have

y = daily cost + 3

mathstudent55 · Answer

Now let's see what happens on each day.
If he rents for 1 day, he pays $8.
We know that $3 is the fixed amount, so we subtract $8 - $3 = $5.
The daily charge for 1 day is$5.

Let's look at the second day just to confirm the daily charge.
If he rents for 2 days, he pays $13.
We subtract the fixed charge to find the daily charge for 2 days: $13 - $3 = $10
$10/2 = $5
Once again, we see he pays $5 per day.

mathstudent55 · Answer

Yes, B and C both have a fixed charge of $8 which is not correct.

Once again, we have

y = daily charge + 3

What is the daily charge in terms of x, the number of days?

This is just the daily charge:
If he rents for 1 day, he pays 5 * 1 = 5
If he rents for 2 days, he pays 5 * 2 = 10
If he rents for 3 days, he pays 5 * 3 = 15
If he rents for x days, he pays 5 * x = 5x

The daily charge is 5x.

What is y, then? (daily charge + fixed charge)

mathstudent55 · Answer

No. I'm not asking for a number.
I didn't tell you how many days he's renting.
I'm asking for the correct expression for the cost.

The rental has a fixed cost of $3 and a daily cost of 5x.
y = daily cost + fixed cost
What is y?

mathstudent55 · Answer

|dw:1468345873296:dw|