Linear Programming Problem with confusing variable?

2. Gillian’s restaurant has an ice cream counter where it sells two main products, ice cream and frozen yoghurt. The restaurant makes one order for ice cream and yoghurt each week and the restaurant has enough freezer space for 115 gallons total of both products. A gallon of frozen yoghurt costs $0.75 while a gallon of ice cream costs $0.93. The restaurant budgets $90 per week for both products. The manager estimates that each week the restaurant sells twice as much ice cream as frozen yoghurt. Profit per gallon of ice cream is $4.15 while profit for yoghurt is $3.60 per gallon.

Formulate a linear programming model for this problem