| $$ \begin{aligned}20x^7y^4-35x^3y^5-15x^6y^5& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}20x^7y^4-15x^6y^5-35x^3y^5\end{aligned} $$ | |
| ① | Combine like terms: $$ 20x^7y^4-15x^6y^5-35x^3y^5 = 20x^7y^4-15x^6y^5-35x^3y^5 $$ |