Getting error when try to add equations line by line in latex

Question

Hi there if any one can help. i want to add equations in latex. My equations are in fraction like precision= T_P/ T-P +f_n and so on in next line i have precision= T_P/ T-P +f_n and son but when I compiled my code in pdf it gives me something which is so wrong if any one can help. I want my equations as define in this image

Here is my code

    \documentclass{article}
\usepackage[utf8]{inputenc}
\title{equation}
\begin{document}
\maketitle
\section{Introduction}
\begin{align*}
Precision =\frac{T_p}{T_p + f_p} \  \%
%%\end{align} 
%%
Recall =\frac{T_p}{T_p + f_n} \

%%
Accuracy = \frac{T_p + T_n}{T_p + f_n+ f_p +T_n} 
%%
\end{align}
\end{document}

Answer 1

Just I add my proposal using align* or an array with the specific interline [.6em] (vertical space between the equation in the array). Peraphs it is better [.7em], but you are free to choose the correct vertical space.

PS: I accept totally the comment of @David Carlisle on the use of \mathrm in math-mode.

\documentclass[a4paper,12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{amssymb}
\usepackage{newtxtext,newtxmath}
\title{equation}
\begin{document}
\maketitle
\section{Introduction}
\begin{align} 
\mathrm{Precision} & =\frac{T_p}{T_p + f_p} \
\mathrm{Recall} & =\frac{T_p}{T_p + f_n}  \
\mathrm{Accuracy}& = \frac{T_p + T_n}{T_p + f_n+ f_p +T_n} 
\end{align}
[
\begin{array}{ll}
\mathrm{Precision} & =\dfrac{T_p}{T_p + f_p}\[.6em]
\mathrm{Recall} & =\dfrac{T_p}{T_p + f_n} \[.6em]
\mathrm{Accuracy} & = \dfrac{T_p + T_n}{T_p + f_n+ f_p +T_n} 
\end{array}
]
\end{document}