How do I combine these? It's a question I need to answer today in math class but I do not get it

Hi Stacy,

You can think of x as the number of things (say apples):

If I have 4 apples and 5 apples, how many apples do I have? (9 apples)

Likewise, you have 4x and 5x, so you have 9x altogether.

similarly, if I have 9 apples and you take away 4 apples from me, how many apples do I have? (5)

likewise 9x - 4x = 5x.

Let's look at 2 items now.

If I have 4 apples and 5 oranges, there is no way you can add them up different they are different items.

So 4x + 5y = 4x + 5y.

Hope this help you have a better understanding of algebra.