Question

there were 20 man they went to a hotel and ate the meal that costs 60 rs each so the paid 60 rs.but the manager told the waiter that there is a offer so you return them rs5. the waiter kept rs2 with himself and gave the three men rs 1 each .but according to my calculation; each paid rs19 so total 19*3 - 57. and the waiter has taken rs 2 total -57+2-59 . so where is the 1 re..................