ⓐ
|
|
| Find Sam’s cost for a week when he drives 0 miles. |
C=0.5m+60 |
| Find C when m=0. |
C=0.5(0)+60 |
| Simplify. |
C=60 |
|
Sam’s costs are $60 when he drives 0 miles. |
ⓑ
|
|
| Find the cost for a week when he drives 250 miles. |
C=0.5m+60 |
| Find C when m=250. |
C=0.5(250)+60 |
| Simplify. |
C=185 |
|
Sam’s costs are $185 when he drives 250 miles. |
ⓒ Interpret the slope and C-intercept of the equation.

The slope, 0.5, means that the weekly cost, C, increases by $0.50 when the number of miles driven, n, increases by 1.
The C-intercept means that when the number of miles driven is 0, the weekly cost is $60.
ⓓ Graph the equation.
We’ll need to use a larger scale than our usual. Start at the C-intercept (0,60).
To count out the slope m = 0.5, we rewrite it as an equivalent fraction that will make our graphing easier.
|
|
|
m=0.5 |
| Rewrite as a fraction. |
m=10.5 |
| Multiply numerator and denominator by 100. |
m=1(100)0.5(100) |
| Simplify. |
m=10050 |
So to graph the next point go up 50 from the intercept of 60 and then to the right 100. The second point will be (100, 110).
