This is equivalent to finding a function g in which

.
We simply reverse the actions of the initial function by adding 81 back and taking the square root. Therefore,

.
Answer:
1st one is 9
2nd one is 6
3rd one is 2
Step-by-step explanation:
2 digit meaning that it has 2 numbers. For example, 66 is a two digit number.
Now, they also said it must be prime, meaning that its factors can only be 1 and itself.
Also, it must be odd.
Answer: 67
Now, do the same, except the number must be composite, as meaning that it has other factors.
Answer: 21
by 2 integers do you mean the same numbers just one negative and one whole?