Find a ⋅ b. a = <2, 4>, b = <2, 5>

A: <4, 9>
B: 24
C: <4, 20>
D: 16

An unknown number of kids and buses are getting assigned. when assigning 4 kids to each bus, there are 2 kids that aren't placed in a bus. when assigning 8 kids to each bus, there are 2 empty buses. how many total kids are there?

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

Collin did the work to see if 10 is a solution to the equation r/4=2.4