how to put equation number FOR MULTIPLE EQUATIONS IN latex code example

Example: multiple math equation in latex

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{equation}
  \label{eq:t}
  \begin{aligned}
    f(x) &= x^2\\        
    g(x) &= \exp(x)
  \end{aligned}
\end{equation}

\begin{equation}
  \label{eq:u}
  \begin{gathered}
    f(x) = x^2\\        
    g(x) = \exp(x)
  \end{gathered}
\end{equation}

\end{document}