Combining Alike Terms

When combining like terms, some people who are not very experienced with this topic commonly do the same thing. This thing is combining things that seem to be alike, but are not.
For example, you can combine -6a+-4a. However you cannot combine them if one of them has an exponent.

For example you cannot combine

, because -4a does not have an exponent.

Here is an example of how to combine like terms,

6a - 5 - 4 - 2a - 7

6a + -2a = 4a

-5 + -4 + -4 = -16

So now after combining the terms that are alike your new equation is,

4a - 16