F(4) if f(x) = -3x + 15 ??

noone has been able to give me the correct answer :(

This is so harddd! solve. 1 + 1 = solve 4 + 4 = solve 3 x 3

Enter the number of complex zeros for the polynomial function f(x) = x 4+ 5x² +6

Arestaurant chef made 1 1/2 jars of pasta sauce. each serving of pasta requires 1/2 of a jar of sauce. how many servings of pasta will the chef be bale to prepare using the sauce?