does a -8 plus -7 equal 15 then?

Think of a number line. You go back 8 and then back another 7. You arrive at a negative 15.

Another analogy. If you borrow $8 from your sister and $7 from your brother, you'll owe $15 (-15.
)

thank you

You're welcome.

No, (-8) plus (-7) does not equal 15. The sum of -8 and -7 is actually -15. Let me explain how to calculate it:

When adding or subtracting two numbers with the same sign (in this case, both are negative), you add their absolute values and give the result the same sign as the original numbers.

In this case, the absolute value of -8 is 8, and the absolute value of -7 is 7. So, when you add 8 and 7, you get 15. Since both numbers are negative, the final answer remains negative, resulting in -15.

Therefore, (-8) + (-7) = -15.