Chapter 4 - Writing Linear Functions - 4.6 - Arithmetic Sequences - Exercises - Page 214: 15

$0.1,-0.2$ and $-0.5$.

Each term is $0.3$ less than the previous term. So, the common difference is $-0.3$. Add $-0.3$ to a term to find the next term. The next three terms are $0.4+(-0.3), 0.4+2(-0.3)$ and $0.4+3(-0.3)$. That is, $0.1,-0.2$ and $-0.5$.