### Still have math questions?

Algebra
Question

The temperature of water in a certain lake on a day in October can be determined by using the model $$y=15.2-0.537x$$ where x is the number of feet down from the surface of the lake and $$y$$ is the Celsius temperature of the water at that depth. Based on this model, how deep in the lake is the water $$9$$ degrees? (Round to the nearest foot.)

$$12~\mathrm{ft}$$