### Instruction: Simplify $(x+15)+(100x+15)$.### Response: To simplify this expression, I need to combine the like terms, that is, the terms that have the same variable part.
I notice that there are two terms with $x$, namely $x$ and $100x$, and two terms that are constants, namely $15$ and $15$.
To combine the terms with $x$, I can add their coefficients, that is, the numbers in front of them.
So $x+100x$ is the same as $101x$.
To combine the constant terms, I can just add them as they are.
So $15+15$ is the same as $30$.