multiply r by t, add the result to u, then multiply what you have by s

multiply r by t, add the result to u, then multiply what you have by s

Take this algebraic expression in parts:

1. Multiply r by t: rt
2. Add the result to u means we add rt to u: u + r
3. Multiply what you have by s. This means we take the result in #2, u + r, and multiply it by s:

s(u + r)