Mary Beth has a farm, and she keeps only sheep and horses. Let $S(t)$ and $H(t)$ stand for the number of sheep and horses, respectively, on Mary Beth's farm in year $t$.
a) Write functions $P_S(t)$ and $P_H(t)$, which give the percentage of sheep and horses, respectively, out of the total number of animals on the farm.
$P_S(t)=$
$P_H(t)=$

b) Evaluate $P_S(t) + P_H(t)$.
$P_S(t) + P_H(t) =$

Hint: