students to student assistants
3rd period is 85:5
fractionify and simplify
85/5=17/1
17:1
7th period is 51:3
51:3
51/3
17/1
17:1
if they are proportional, then they are equal when simplified
17:1 is 3rd period
17:1 is 7th period
they are equall
they are poropoertional