Hi,
Tickets= -0.4x^2+20x+122.1
a) downward, coefficient of the squared term is negative
b) substitute values of 10,20,40,50 for x to obatain number of tickets
c)
x = -5.5 and x = 55.55 the last day tickets will be sold
d) 55.55 - 60.05/2 = 25.525
e. calculate value of x = 25.525 for the number of tickets
f) answers to d and e are the vertex points
will let you finish up