Let the price of the tickets be 'x' and the number of tickets bought is 'y'
When the y inversely proportioned to x, the equation is
y = k/x where k is a constant
We work out the value of k by using the information y = 6 and x = 5
6 = k/5
k = 30
Hence, the maximum number of tickets when the price is $3 is
y = 30/3
y = 10 tickets