I suppose what makes this question annoying is that there is the question mark so what i'll do first is substitute the question mark with x. also, there are annoying parenthesis so we'll first eliminate the ones we don't need. now we just have to solve for x.
-3.4 + (-8 + 2) = (x + (-8)) + 2
adding a negative number is subtracting that number so x + (-8) = x - 8
-3.4 + 2 - 8 = x - 8 + 2
-3.4 -6 = x - 6
x = -3.4
make sure you are aware that the negative sign belongs to the number after it so -2 + 4 is not -(2+4) = -6 but rather 4 - 2 = 2.
let me know if you have any questions!
