Chemistry Examples

$- 9.9 - - 2$

Step 1

Replace all occurrences of $-$ $-$ with a single $+$ . Two consecutive minus signs have the same mathematical meaning as a single plus sign because $- 1 \cdot - 1 = 1$

$- 9.9 + 2$

Step 2

Add $- 9.9$ and $2$ .

$- 7.9$