I have the following expression:
\begin{equation}
\begin{aligned}
%C1
\sum_{i = 1}^{m}{y^{C_1}_i} &= m\beta_0^{C_1} + \beta_1^{C_1}\sum_{i = 1}^{m}{x_{i1}^{C_1}} + \cdots + \beta_q^{C_1}\sum_{i = 1}^{m}{x_{iq}^{C_1}}\\
\sum_{i = 1}^{m}{y^{C_1}_ix_{i1}^{C_1}} &= \beta_0^{C_1}\sum_{i = 1}^{m}{x_{i1}^{C_1}} + \beta_1^{C_1}\sum_{i = 1}^{m}{(x_{i1}^{C_1})^2} + \cdots + \beta_q^{C_1}\sum_{i = 1}^{m}{x_{iq}^{C_1}x_{i1}^{C_1}}\\
&\vdots\\
\sum_{i = 1}^{m}{y^{C_1}_ix_{iq}^{C_1}} &= \beta_0^{C_1}\sum_{i = 1}^{m}{x_{iq}^{C_1}} + \beta_1^{C_1}\sum_{i = 1}^{m}{x_{i1}^{C_1}x_{iq}^{C_1}} + \cdots + \beta_q^{C_1}\sum_{i = 1}^{m}{(x_{iq}^{C_1})^2}\\
%C2
\sum_{i = 1}^{m}{y^{C_2}_i} &= m\beta_0^{C_2} + \beta_1^{C_2}\sum_{i = 1}^{m}{x_{i1}^{C_2}} + \cdots + \beta_q^{C_2}\sum_{i = 1}^{m}{x_{iq}^{C_2}}\\
\sum_{i = 1}^{m}{y^{C_2}_ix_{i1}^{C_2}} &= \beta_0^{C_2}\sum_{i = 1}^{m}{x_{i1}^{C_2}} + \beta_1^{C_2}\sum_{i = 1}^{m}{(x_{i1}^{C_2})^2} + \cdots + \beta_q^{C_2}\sum_{i = 1}^{m}{x_{iq}^{C_2}x_{i1}^{C_2}}\\
&\vdots\\
\sum_{i = 1}^{m}{y^{C_2}_ix_{iq}^{C_2}} &= \beta_0^{C_2}\sum_{i = 1}^{m}{x_{iq}^{C_2}} + \beta_1^{C_2}\sum_{i = 1}^{m}{x_{i1}^{C_2}x_{iq}^{C_2}} + \cdots + \beta_q^{C_2}\sum_{i = 1}^{m}{(x_{iq}^{C_2})^2}\\
%R
\sum_{i = 1}^{m}{y^{R}_i} &= m\beta_0^{R} + \beta_1^{R}\sum_{i = 1}^{m}{x_{i1}^{R}} + \cdots + \beta_q^{R}\sum_{i = 1}^{m}{x_{iq}^{R}}\\
\sum_{i = 1}^{m}{y^{R}_ix_{i1}^{R}} &= \beta_0^{R}\sum_{i = 1}^{m}{x_{i1}^{R}} + \beta_1^{R}\sum_{i = 1}^{m}{(x_{i1}^{R})^2} + \cdots + \beta_q^{R}\sum_{i = 1}^{m}{x_{iq}^{R}x_{i1}^{R}}\\
&\vdots\\
\sum_{i = 1}^{m}{y^{R}_ix_{iq}^{R}} &= \beta_0^{R}\sum_{i = 1}^{m}{x_{iq}^{R}} + \beta_1^{R}\sum_{i = 1}^{m}{x_{i1}^{R}x_{iq}^{R}} + \cdots + \beta_q^{R}\sum_{i = 1}^{m}{(x_{iq}^{R})^2}
\end{aligned}
\label{eq:normals_equations}
\end{equation}
and I want to place brace of this form: