(plz hlp me asap)
which expression is the multiplicative inverse of r, where r is a non-zero number?
a. -1/r
b. - r
c. 1/r
d. 2r

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236