Kiera G. answered • 05/25/19

Experienced Tutor in Mathematics & Computer Science

We have two variables, a y for **total** *cost* and an x for number of **miles**, and we have two numbers, $.20**/mile** and $.70**/day**.

Most of the time, the y is by itself on the left side of the equation (especially if it represents a **total**).

If we're saying this all happens in **1 day**, $.70 goes by itself too. Really we multiply .70/day by 1 day, and *the "day"s cancel out*.

This leaves .20/mile and x for the number of miles, which we are also going to multiply. This *cancels out the miles* and leaves $.20x.

Now that all our terms are in dollars (remember, y is cost, which is a unit of money), we can put stuff together.

y = .20x + .70

This is our function. Since x is not squared or cubed or anything, we know this is a straight line, so all we have to do is find two points and connect them.

The easiest points to find are when x=0, and when x=1.

When x = 0, y = .70 since the x term is equal to zero.

When x=1, y = .20 + .70 = .90

Now we have two pairs: (0, .70) and (1, .90). Graph these, and draw a straight line connecting both.

For the last part, simply choose an x value and plug it into the equation .20x + .70.

I hope this answers your question!