Problem $2.($a$)$ A school offers $3$ chemistry classes, $4$ biology classes, $1$ physics class, and $10$ math

classes $($because math is amazing$).$ How many schedules can you make comprised of one class each

in chemistry, biology, physics, and math?

$($b$)$ How many words $($whether they have meaning in any language or not$)$ can be made with the letters

$H,E,L,$ and P without repeating any letters?

$($c$)$ In how many ways can a CRA auditor choose $5$ tax returns out of $36$ for a special audit?