Write an expression for the sum of nine and 𝑓.
First, we need to think about what the word “sum” means. When we talk about the sum, we know that we’ll be doing addition. The addends are the two things you’ll be adding together. For us, that’s the nine and the 𝑓. Because we know that it’s a sum, we put an addition symbol between them. An expression for the sum of nine and 𝑓 is nine plus 𝑓.