Question 112801
Example 1:   Simplify  by combining like terms. 

Are there any like terms that we can combine?  
It looks like it.  Both terms have the same variable part, a. 

7a-10a
(7-10)a
-3a

Simplify 5x^2+7x-2x^2-10x+5
It looks like we have two terms that have an x squared that we can combine and we have two terms that have an x that we can combine.  The poor 5 does not have anything it can combine with so it will have to stay 5.  
Grouping like terms together and combining them we get:

5x^2+7x-2x^2-10x+5
5x^2-2x^2+7-10x+5
3x^2-3x+5