In certain deep parts of oceans, the pressure of sea water, $\displaystyle {P},$ in pounds per square foot, at a depth of $\displaystyle {d}$ feet below the surface, is given by the following equation:

$\displaystyle {P}={16}+\frac{{{4}{d}}}{{13}}$

At a depth of 689 feet below the surface, what is the pressure of the sea water?

pounds per square foot