Question 888643
You can find this equation by noticing the pattern.

If n=1 ticket, the cost {{{C=40$}}} You could also write this as {{{C=40 x 2 ^0}}} since {{{2^0= 1}}}, this will be useful;
If n=2, the cost of one ticket is {{{C = 40 x 2 = 80$}}};
If n=3, the cost of one ticket is {{{C = 40 x 2 x 2 = 40 * 2^2 = 160$}}};
If n=4, the cost of one ticket is {{{C = 40 x 2 x 2 x 2 = 40 x 2^3 = 320$ }}}

For an arbitrary n number of tickets, the equation is thus {{{C = 40 x 2^(n-1)  }}}