At the surface of the ocean, the water pressure is the same as the air pressure above the water, about $15 \quad lb/in^2$, Below the surface the water pressure increases by about $3.74 \quad lb/in^2$ for every 10 ft of descent.
Write a function $f(x)$ which expresses the water pressure in pounds per square inch as a function of the depth in inches below the ocean surface.
$f(x) =$
At what depth is the pressure $100 \quad lb/in^2$? Include the units in your answer: