Answer:
if 10 of them costs $7.90 then 50 would cost $39.50.
there are two different ways of doing this:
1. you could divide $7.90 by 10 which would get you $0.79 (the price of one frozen juice bar) then multiply $0.79 by 50 to get $39.50 (the price of 50 frozen juice bars)
or
2. you could just take $7.90 and multipy it by 5 (b/c 10 x 5 is 50)
