# How do you evaluate −7 − 8 ?

Jun 17, 2018

$- 15$ is the answer.

#### Explanation:

You are subtracting. So -7-8 gives us $- 15$

Jun 17, 2018

Most likely: $\textcolor{red}{- 15}$
Alternate possibility: $\textcolor{b l u e}{+ 1}$

#### Explanation:

In general PEDMAS is normally specified as being evaluated from left to right (when operations are at the same level).
Therefore $- 7 - 8$
would be evaluated as $\textcolor{red}{\left(\left(- 7\right) - 8\right) = - 15}$

However, I have encountered some computer programming languages/environments that claim to be PEDMAS but which evaluate right to left,
in which case $\textcolor{b l u e}{- 7 - 8 = \left(- \left(7 - 8\right)\right) = \left(- \left(- 1\right)\right) = + 1}$