First you plug in the the variable values.
24/4 × 3 - 6/3 + 8.
Then you follow the procedure using order of operations (First you do multiplication/division right to left, then subtraction/addition)
24/4 is 6, then multiply by 3 which is 18.
So far you have 18 - 6/3 + 8. Then you divide 6/3 because it is division and you get 2.
18 - 2 + 8, then you subtract 2 from 18 to get 16 and add 8 which is 24. So the answer is D