Example

Finding a Temperature Difference Using Integer Subtraction

When finding the difference between two temperatures — one positive and one negative — the keyword difference signals subtraction. For example:

Problem: In the morning the temperature was 1111 degrees; by mid-afternoon it had dropped to 9-9 degrees. What was the difference between the morning and afternoon temperatures?

  1. Identify what to find: the difference of the morning and afternoon temperatures.
  2. Write a phrase: "the difference of 1111 and 9-9."
  3. Translate: 11(9)11 - (-9).
  4. Simplify: Subtracting a negative is the same as adding a positive, so 11(9)=11+9=2011 - (-9) = 11 + 9 = 20.
  5. Answer: The difference in temperatures was 2020 degrees.

This example shows how the rule a(b)=a+ba - (-b) = a + b arises naturally in everyday temperature calculations.

Image 0

0

1

Updated 2026-04-21

Contributors are:

Who are from:

Tags

OpenStax

Elementary Algebra @ OpenStax

Ch.1 Foundations - Elementary Algebra @ OpenStax

Algebra

Math

Prealgebra

Related
Learn After