Is this a function ? Yes or no and why or why not

Describe the 2 algebraic methods you can use to find the zeros of the function f(t)=-16t^2+400.

Sheila wants to bake six muffins but the recipe is for 12 muffins . this means you only need half of the ingredients listed how much of the of each ingredient does she need? one cup and banana chips ,7 tablespoons oil , two eggs, 3/4 cups flour 1/4 cup walnuts show all you work and justify your answer using a baby toulmin.

An investment decreases in value by 30% in the first year and decreases by 40% in the second year. what is the percent decrease in percentage in the investment after two years