Marti brought 20 juice boxes to the party. The guests drank 6/8 of the juice boxes.
2 answers:
You might be interested in
Hmm, seems to multiply by 5
wait, no
first is multiply by 5
2nd is multiply by 10
3rd is multiply by 15
4th is multiply by 20
seems to be
or 
the rule is square the input then multiply by 5
wait, no
first is multiply by 5
2nd is multiply by 10
3rd is multiply by 15
4th is multiply by 20
seems to be
the rule is square the input then multiply by 5