 So let's try to add and simplify a rational expression. So if we're not so lucky as to have two rational expressions with the same denominator, we can find a common denominator by multiplying the denominators together. And so the common denominator will be, and it's useful to remember that factored form is best, and so that unless we have a good reason for multiplying things out, we'll leave them in factored form. So our first rational expression has the factor a plus nine, but it's missing the factor a plus one. So we'll multiply numerator and denominator by a plus one. Now while factored form is best, we are going to have to do something with the numerator, so we'll multiply it out to get. However, the denominator isn't going to change, so we'll leave it in factored form. Now our second rational expression has the factor a plus one, but it's missing the factor a plus nine. So we'll multiply numerator and denominator by the missing factor. We'll expand the numerator, and we'll keep the denominator in factored form, although we'll reverse the order of the factors so that they're the same as in the other rational expression. So now our two rational expressions have the same denominator, so we can add the numerators together. And let's go ahead and enter it. So remember, computers are essentially honest. They don't really care what you meant. They don't really care what you intended. They don't read anything into what you've said. They go by exactly what you write. And so here's the important thing. This is what we actually want to write as our answer, which means that we have to tell it to the computer in a way that it understands what we wanted. So if we type this, well, first of all, it objects. It says there's a syntax error, and it suggests we might want to check our variables. And we realize that the problem is in variable A, and we typed an answer in variable X. So let's fix that. And while we've changed the variable so that it now accepts the syntax, this isn't what we wanted to write. And to fix that, we'll have to make sure that the numerator and denominator are enclosed in parentheses. And as long as what the computer understands is what we wanted to write, we should be OK. Let's submit and get the full credit for the problem.