| Reverse Process |
| :---: | :---: |
|  | [ Arithmetic. Mental calculation, etc.] |
|  | [ Word problems (miscellaneous).  [ Iterations |

John had a full basket of trampolines. First, he met Anna and gave her half of his trampolines and another half trampoline. Then he met Banna and gave her half of the remaining trampolines and another half trampoline. After meeting Vanna and giving her half of the trampolines and another half trampoline, the basket was empty. How many trampolines did John have at the beginning? (It was not possible to find out what trampolines are, as there were none left by the end of the problem.)

#
Notice that before meeting Vanna, John had one tremponch left, as half of this amount was half a tremponch. Before meeting Banna, he had 3 tremponchs, because half of this amount was one and a half tremponchs, that is, one and a half. Similarly, we get that initially there were 7 tremponchs.

## Answer

7 tremponchs.