3 people decide to buy a t.v. and it costs £30 (ok, a cheap t.v) any way one they buy it the manager tells them that there is 5 pounds knocked off the tv and they each take £1 back and are left with 2 pounds, so that means each person has payed £10 minus £1 so they have each spent £9, 3 times 9 is £27 and there was £2 left over,

That totals to £29, where has the other pound gone??