```
\begin{equation}
\lefteqn{TPR=\frac{\sum_{i=1}^{N}\sum_{j=1}^{S}S_{SU_{ij}=1\mid PU=1 }}{\sumS_{PU=1}}*N}
\label{eqn:6}
\end{equation}

```

I am trying to write this equation. The denominator part is not coming proper and i am not able to left align the equation. I am in a two columned format. The problem is the equation is moving to the second column.