solve this if you are a genius

3 persons went to the hotel for dinner, the bill was 70rs,

each gave 25rs so 25*3=75

waiter kept two ruppees as tips and returned 3rs back, so 1rs for each person,

so each person contributed (25-1)=24rs,

totally 24*3=72, + 2rs tips = 74,

find where is the remaining one ruppee...?