Unclear of the question, but the value is already as a mixed fraction. The value of absolute value is just the distance from zero. So, |-4|=4 or |6|=6
Sure ... exactly the way you simplify "2 + 2" when it comes up in conversation ... perform the indicated operation wherever possible. In simplified form, -4x-x is written as. " -5x ".
I will assume that this question is about scientific notation (also assuming that the first number is 3.4*10^2), where you can arrange the numbers by the exponent of the 10, so from least to greatest:

,

, 435, and