Find All Fixed Points for the Function by Setting the Function

Multiple Choice

Find all fixed points for the function by setting the function equal to x and solving the resulting equation for x.
-A projectile is launched upward from an initial height of 360 feet, and it lands on the ground after 6 seconds. What was the initial velocity of the projectile?

A) 26 feet/second
B) 36 feet/second
C) 46 feet/second
D) 30 feet/second