Evaluate -1 - (-2) -10

Explanation

This expression involves two subtractions.  We will write each subtraction as addition of the opposite and then evaluate the expression using the order of operations rule.  It is each to make an error when subtracting signed numbers.  We will probably be more accurate if we write each subtraction as addition of the opposite.

We apply the rule for subtraction twice and then perform the additions, working from left to right.  (We could also add the positives and the negatives separetely, and then add those results.)

• Add the opposite of -1, which is 2.  Add the opposite of 10, which is -10.
  • -1 - (-2) - 10 = -1 + 2 + (-10)
• Work from left to right.  Add -1 + 2 using the rule for adding integers that have different signs.
  • = 1 + (-10)
• Use the rule for adding integers that have different signs.
  • = -9