What are the factors of 64

Find the maximum value of p= 4x + 5y subject to the following constraints :

Ineed to know the ordered pairs for this equation i need the answer quick because it’s a timed test

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?