Answer :
Let's begin by listing out the given information:
[tex]\begin{gathered} 7.3+(2+(-3.1)) \\ The\text{ }commutative\text{ }property\text{ }of\text{ }addition\text{ i}s\text{ shown below:} \\ a+b=b+a \\ \Rightarrow(-3.1)+2)+7.3 \\ The\text{ }associative\text{ }property\text{ }of\text{ }addition\text{ i}s\text{ shown below:} \\ \mleft(a+b\mright)+c=a+\mleft(b+c\mright) \\ (-3.1)+2)+7.3=7.3+(-3.1)+2) \\ \\ \therefore7.3+(-3.1)+2) \end{gathered}[/tex]Therefore, the answer is: 7.3 + (-3.1) + 2)