Check the picture below
in case you want to know how to get who's the adjacent or opposite, notice in the picture, if you put your eye on the angle itself, what you'd be facing is the opposite side, the adjacent is the side touching the angle.
8 in 2.408 is closer to 10, so you round 2.408 to 2.41
The initial expression is:
2x + 4(x - 2)
Replacing x by 3, we get:
2(3) + 4(3 - 2)
6 + 4(1)
6 + 4
10
The value of the expression is 10
-2 + 8 = 6
because if you have 2 negative circles ●● and 8 positive circles ○○○○○○○○ then once you take away the first two circles you get you answer. You do the opposite. :) ( hope that make sense... )