F(z) = 6z2 – 13z + 14 and g(z) = 5z2 – 3z + 12, find f(z) – g(z)

Milk and ice cream are mixed together for a recipe. the total volume of the mixture is 1 cup. if the milk contains 2% fat, the cream contains 18% fat ,and the mixture contains 6% fat ,how much cream is in the mixture