Sally Has Been Running the Following Number of Ads in the Local

Essay

Sally has been running the following number of ads in the local newspaper to help attract customers into her store. She has also been keeping track of customers who have come into the store as a result of the ads, as well as the amount of money they spend.
This is the data from the last 4 weeks:
$$\begin{array} { c c } \text { Number of ads } & \text { Increased sales } \\\hline 16 & 330 \\12 & 270 \\18 & 380 \\14 & 300 \\\hline\end{array}$$
-If Sally runs 10 ads, how much will sales increase?