Now start,
There are three person A, B and C.
each one have $20, i mean A have $20, B have $20, C have $20.
They Contribute and equal to A+B+C=20+20+20;
i mean total $60,
when they reach a shop a shop's servant meet and buy a Gift worth Rs. $60, by the shop's servant,
when the shopkeeper come on the shop and ask the question to the servant how much cost you sell that gift, servant says $60.
Shopkeeper told her but Actual cost is Worth Rs. $50, why are you sell with $60 cost, Please go to return her $10,
Servant goes to the buyer house and in between the way he spend $4 in taxi fair so he only return $6 to the buyers,
They A,B and C are Divide $6 in three part and take it. i mean less $2 what they pay $20. so each one pay Now $20-$2=$18,
When the servant come to the shop,
he gives the solution of the Total Cost of Gift
$18+$18+$18=$54(actual Cost)
He also spend $4 So he add $54+$4=$58
then shopkeeper told to servant where $2 goes.
if we add $54+$6=$60 then where we say that servant spend $4, there is no clue about servant fair. either they pay $56 +$4 and if They pay $56 then how this can possible. actually they pay only $54 by the calculation this is clear. any way try to find out the actual calculation of this funny joke.
thanks
Every person started with $20 and ended up with $2, which means that they spent $18 each. Three times eighteen is 54 dollars which is $50+$4 - the price of the gift and the price of the taxi ride 
