The question is for 1980, trough 1990, the total amount, $A$ (in billions of dollars), spent by Americans for the farm foods can be modeled by $$ A = -0.035t^2 + 15.9t + 267.6$$ where $t=0$ represents 1980. The amount, $F$ (in billions of dollars), paid to farmers can be modeled by $$ F = 0.156t^2 + 0.475t + 81.5 $$ Find the model that represents the amount that was spent on processing, packaging and marketing the food.
For this problem I don't even understand what i have to do to solve it? Do i use the calculator, if so how would i do it? Any ideas on how to solve them?