I could be wrong, but I'll try my best.
So typically the formula to find the volume of something is l×w×h (length times width times height).
The length is 8, the width is 6, and the height is 9 in this equation.
To find the volume we gotta multiply all of this together. When we multiply 8×6×9, we should get 432. I could be wrong, sorry if I am.
edit; I realise I forgot the division part, and someone else's answer brought that to my attention. The true answer is 144. You have to divide 432 by 3 to get that. Check out the other answer, they got it completely correct