A product is the answer that you get when you multiply numbers together. So for this problem, you have 2 groups to multiply together. Since I cannot show a square or cubed x, I will put an x2 for x squared and an x3 for x cubed. You have to multiply each number in the first parentheses by each number in the second parentheses. Then combine any like sets.
(8x-3)(x2-4x+8)
8x3-32x2+64x-6x+12x-24
8x3-32x2+70x-24
So the answer is 8x cubed minus 32x squared plus 70x minus 24. Whew! That's a long one. Hope I didn't miss anything.

now, a line perpendicular to that one, will have a "negative reciprocal" slope, thus
The pattern is dividing by 4 so it would be: 640 (divided by 4), 160 (divided by 4), 40 (divided by 4), 10 (divided by four), 5/2.
The next number would be 10/4 or 5/2 when simplified. (I’d go with 5/2 because teachers liked simplified numbers)