The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

The first one:

you have one ++x so x becomes 11 (preceeding increment is done before the variable is taken in the other operation)

after that is executed the summing x + x, so the sum becomes 22

and finally is executed x++ so x becomes 12.

The second one:

the first two x are summed up (they are with postfix inc so they are still 10)

at this point the sum is 20

after that this sum has to be summed up with the thirs x, but there we have prefix inc so x becomes 11, and the sum becomes 20+11=31

after that the postfix increment of the first two x is done so x becomes 13.

The third one:

The first two x are summed up, the one of them is wirh prefix inc, so x becomes 11 and the sum at this point is 22. After that the thirs x comes, it is with postfix inc so the x is still 11 and the sum becomes 33. After that the 4th x comes, it is with prefix inc so x becomes 12 and the sum becomes 45. after that the two postfix increments are done and the x becomes 14.

Hopes that helps!