Deniz tried to subtract two polynomials. Her work is shown below:
$\begin{align}
&\phantom{=}(3r^2-9r+3)-(-5r^2+7r-2)
\\\\
&=3r^2-9r+3+5r^2-7r+2&\text{Step }1
\\\\
&=(3-9)r^2+(5-7)r+(3+2)&\text{Step }2
\\\\
&=-6r^2-2r+5&\text{Step }3
\end{align}$
**At which step did Deniz make an error, if at all?**
[[☃ radio 2]]