How and When to Cancel Things in Fractions

One of the common errors in algebra is canceling bits in fractions that can’t be canceled. To remember the rule, though, you don’t have to memorize anything. You only have to think of a plain arithmetic problem to compare it.

To help you remember what’s allowed with problem:

think about this simpler problem:

Like this:

And just to keep you straight, here are the requirements (and a couple of examples) for the fancy <cue music> “distributive property.”

What do you think of this explanation? Post your thoughts in the comments.