the variable m varies directly w the square of n and inversely with the square root of p. When n=4 and p=16 then m=8. Write the equation which describes the relationship between m, n and p

Becca wants to mix fruit juice and soda to make a punch. she can buy fruit juice for $3 a gallon and soda for $4 a gallon. if she wants to make 28 gallons of punch at a cost of $3.25 a gallon, how many gallons of fruit juice and how many gallons of soda should she buy?