Hello!
You can only add variables with the same base and exponent
8u^3 + 4u^3 = 12u^3
8u^2 + 0 = 8u^2
0 + -6u = -6u
6 + 3 = 9
Put the sums together
12u^3 + 8u^2 - 6u + 9
The answer is

Hope this helps!
The correct answer is C. They are going down by 3.
Always use the formula (y2-y1)/(x2-x1) to find a line’s slope, given two points:
(-1- -8)/(4-5) = 7/-1 = -7
-7 is the slope
because in each case, the selected column composes one<span>-tenth of the grid in total. The number of blocks is different, but the proportion of space filled is the same.</span>