| $$ \begin{aligned}27s^4+0.135s^3-7.655E-10& \xlongequal{ }27s^4+0s^3-7.655E-10 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}27s^4\end{aligned} $$ | |
| ① | Combine like terms: $$ 27s^4 = 27s^4 $$ |