Potential energy ball fall halfway, 20 meters high

Suppose y varies directly with x. write a direct variation equation that relates x and y. then find the value of y when x=12 y=7 when x=3

Describe how to determine the average rate of change between x = 4 and x = 6 for the function f(x) = 2x^3 + 4. include the average rate of change in your answer.

Solve the system of equations. x=-2y+1 and x+2y=9. show work