Larry earned $11 walking his neighbors' dogs on saturday. he earned some extra money on sunday doing the same thing. write an expression with a variable that shows the total amount of money larry has earned saturday and sunday.

This is easy. He first earned $11 on Saturday and then on Sunday he earned some money. We don't know how much he earned, we just know he earned some money. Let's put the expression together. A good place to start would be the $11. Let's add eleven to the expression. And because he earned some more money, it's going to be addition. So currently, the expression stands at $11 + 
And because we don't know how much money he made on Sunday, x will be the variable for how much he earned. So the expression will be 

11 + x