Three men in a resturant ordered for a meal, the total cost of which is N15. They each contribute N5. The waiter takes the money to the chef who recognizes the three as friends and asks the waiter to return N5 to them.
The waiter is not only poor at mathematics but dishonest and instead of going to the trouble of spliting the N5 between the three, he simply gave them N1 each and pockets the remaining N2 for himself.
Now, each of the men effectively paid N4, the total paid is therefore N12. Add the N2 in which the waiter pockets and it becomes N14.
Where has the original N1 gone from the original N15?

10 naira is what ends up in the company wallet
2 naira in the waiter's wallet
3 naira goes back to these gents

10 in the coy's wallet plus 2 in the waiter's is what these guyz believe they paid which is 12

asking us to add 2 to the 12 the second time is a failed attempt at creating confusion.