Question 880782
Is that all the information given?  If so, there are many possibilities.  Anything that fits the formula 2A + C = 55.  Let's narrow them down by assuming that they are whole numbers, and that adult tickets cost more.  In that case, your possibilities are:
A / C  (2A + C = 55)
27, 1   27*2 + 1 = 55
26, 3
25, 5
24, 7
23, 9
22, 11
21, 13
20, 15
19, 17