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This looks a bit creepy, but it's really easy if you are good at finding the opposite of a number and adding signed numbers.

You can review finding the opposite of a number here.

And I'm totally serious about the adding thing!  You need to have the previous two lessons on adding signed numbers (integers) down cold... or this lesson is going to give you a major headache.

OK, if you're ready, let's go!

Here's a regular, old subtraction example:

8 - 3 = 5

That's easy stuff.

And, now that we have negative numbers, we can do this:

3 - 8 =

number line showing that 3 - 8 = -5

3 - 8 = -5

Hey, that's the exact same thing as when we did this:

3 + -8 =

number line showing that 3 + -8 = -5

3 + -8 = -5

Don't let the different way of writing this mess with your head.  It's just a different notation.