Horizon.

$D_S=221-0\mathrm{.}60P_S+0\mathrm{.}35P_H$

$D_H=267+0\mathrm{.}10P_S-0\mathrm{.}64P_H$

a$)$ The store wishes to determine the selling price that maximizes revenue for these two products. Develop the revenue function for these two models. $($Enter your answer in terms of $P_S$ and $P_H.)$

b$)$ Find the prices that maximize revenue. $($Round your answers to two decimal places.$)$