Solving the problem by working backward.
For Question number 8:
The final number is given as 8 (which is the result of all the operations)
Working backwards, Firstly we need to undo the addition of 4 by subtracting 4 from the result.
secondly, we will undo the division by 3, by multiplying the result above by 3.
Then we have our answer.
The number is 12