#### Answer

10s

#### Work Step by Step

The distributive property holds that $a(b+c)=ab+ac$ (for real numbers $a$, $b$, and $c$).
Therefore, $s+9s=(1+9)s=(10)s=10s$.
In this case, we have used the distributive property in reverse to write the given sum as a product. Recall that the coefficient in front of the first term $s$ is 1.