Answer: [tex]d.\ 6 + (-15)[/tex]
Step-by-step explanation:
The missing options are:
[tex]a.\ 15 + 6\\b.\ -6 + (-15)\\c.\ 15 + (-6)\\d.\ 6 + (-15)[/tex]
For this exercise it is important to remember the mulitplication of signs:
[tex](+)(+)=+\\(-)(-)=+\\(-)(+)=-\\(+)(-)=-[/tex]
By definition, the sum is the result of an addition.
Therefore, you need to add the numbers given in the exercise (-15 and 6) in order to find its sum. This is:
[tex]-15+6=-9[/tex]
(Since the greatest number has a negative sign, the sum is negative).
Knowing this, you can check each option to find the expression whose sum is -9:
[tex]a.\ 15 + 6=21\\\\b.\ -6 + (-15)=-6-15=-21\\\\c.\ 15 + (-6)=15-6=9\\\\d.\ 6 + (-15)=6-15=-9[/tex]
The answer is the option "d".
