HELP I HAVE A QUICK CHECK I HATE DIS BEACH

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

Askateboard ramp is in the shape of a right triangle what is the height of the ramp

Consider a bag that contains 220 coins of which 6 are rare indian pennies. for the given pair of events a and b, complete parts (a) and (b) below. a: when one of the 220 coins is randomly selected, it is one of the 6 indian pennies. b: when another one of the 220 coins is randomly selected (with replacement), it is also one of the 6 indian pennies. a. determine whether events a and b are independent or dependent. b. find p(a and b), the probability that events a and b both occur.