| $$ \begin{aligned}3x^2-4x+3y-2.85xy& \xlongequal{ }3x^2-4x+3y-2xy \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}3x^2-2xy-4x+3y\end{aligned} $$ | |
| ① | Combine like terms: $$ 3x^2-2xy-4x+3y = 3x^2-2xy-4x+3y $$ |