-2-(+7) is the same thing at -2-7 which is -9
[tex]-3 \frac{2}{7} -(- \frac{5}{7} )[/tex] is the same thing as [tex](-3 \frac{2}{7}) + (\frac{5}{7})[/tex] which is [tex]- \frac{18}{7}[/tex] or [tex]-2 \frac{4}{7} [/tex]
Last but not least the last one is the Associative Property based on definition listed below :)
Associative Property: When three or more numbers are added, the sum is the same regardless of the grouping of the addends. For example (2 + 3) + 4 = 2 + (3 + 4)
