Solution :
It says multiply 8 by 12 and then add 9
reading the sentence it is clear that priority is given to multiplication of 8 and 12 , once it is done then we would add 9 .
Let us first write multiplying 8 and 12 which makes it 8 x 12
the result is being add to 12 so we place 8x12 in parenthesis then add 12
which , makes it : ( 8x12) + 9
this matches to now of the given options so it is because multiplication is always given a priority comparing to addition so here parenthesis is not that important .
we can write it without parenthesis like : 8x12 +9
Answer is third option .