A factory's production is modeled by function f(x), where f(x) is the number of parts produced per hour and x is the number of people working during production Choose the ordered pair that represents a possible domain and range of the function

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?