### What function?

Can you work out what function has been carried out on the numbers on the left to change them to the numbers on the right?

input | function | output | ||

3 | ? | 15 | ||

12 | ? | 24 | ||

7 | ? | 77 | ||

14 | ? | -1 | ||

120 | ? | 60 | ||

49 | ? | 7 | ||

23 | ? | -5 | ||

0 | ? | 17 |

Is there only one right answer? - or can you think of more than one function to give the same output?