Answer:
The first thing you ever do when simplifying an expression is distributing the coefficient. For example the expression 3(5x+6+4x) The first thing we would do is distribute the 3 into each value in the parantheses. It would make sense to add the 4x and 5x, but that goes out of order. This is just the rules when it comes to follwing distributive property in it's simplest form.
