A company's profit , in thousands of dollars, is linearly related to the number of units , in thousands, that it sells. The table below shows the profit for two different sales volumes.
| u (thousands of units) | P(u) (thousands of dollars) |
|---|---|
| 10 | 55 |
| 30 | 125 |
Which equation represents the relationship between the number of units sold and the profit?
