A nubmer is divided by 2, then 6 is submtacted from the result.

what operations are needed to return to the original number?
I am going to say:
x/2 -6 the operations needed are
multiplication and addition to get right answer?

no,

you have to do it in reverse order and perform the inverse operation.
that is, add 6, then multiply by 2

e.g. let original number be 20
divide by 2 ---> 10, then subtract 6 ----> 4
add 6 to 4 ---> 10, multiply be 2 ---> 20 , our original number.