I don’t know the answer can anyone help

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Create a graph for the demand for starfish using the following data table: quantity/price of starfish quantity (x axis) of starfish in dozens price (y axis) of starfish per dozen 0 8 2 6 3 5 5 2 7 1 9 0 is the relationship between the price of starfish and the quantity demanded inverse or direct? why? how many dozens of starfish are demanded at a price of five? calculate the slope of the line between the prices of 6 (quantity of 2) and 1 (quantity of 7) per dozen. describe the line when there is a direct relationship between price and quantity.

Larger pets need to be transported in larger portable kennels. using a graphing calculator and the relationship between the width, length, and height, find the dimensions of a portable kennel whose volume is 7.4 ft3. the dimensions of a portable kennel can be expressed as width x, length x + 0.4, and height x − 0.2? what are the dimensions of a portable kennel with a volume of 7.4 ft3? use a graphing calculator to solve. round the dimensions to the nearest tenth.