A 7-day pass to all art galleries for one person costs $110. The management gives a concession to a group of 55 tourists. For every 3 tourists who purchase the 7-day pass, the 4th tourist gets free access to the art galleries. How much does each tourist pay in this arrangement if they share the total cost equally?
For every 3 tourists, 4th tourist gets free access.

Number of tourists in eact set
= 3 + 1
= 4

Number of sets of 4 tourists
= 55 ÷ 4
= 13 r 3 

There are 13 sets of 4 tourists in 55 tourists, so 13 tourists will get free access.

Number of tickets to be paid for
= 55 - 13
= 42

Total cost of tickets
= 42 x 110
= $4620

Cost for each tourist
= 4620 ÷ 55
= $84
 
Answer(s): $84