Combine the like terms to make a simpler expression: 4n+6+n−2

When you "combine like terms", you are putting together terms that look similar. For example, 4n and n look similar, because they both have an "n". Imagine the n's are apples, and numbers without 'n' are oranges.
If you have 4 apples, and add 1 apple, you have 5 apples, or 5n.
If you have 6 oranges, and take away 2, you have 4 oranges. But, you can't put apples and oranges together, they are 2 different fruits. 

So, you're left with 5n+4!

The like terms are 4n and n because they both share the n in common. Since the 4n is positive and the n is also positive, the are going to be added together, making 4n + n = 5n. You do the same for the 6 and -2. Since the 6 is positive and the 2 is negative, you subtract 6 and 2, making 6 - 2 = 4.
So the final answer would be:
5n+4

Number nine is f(x)= 40x : ) hoped i ya