\documentclass[12pt]{article}
\usepackage{amsmath, amssymb, graphicx, array, fancyhdr, unicode-math, multirow}

\DeclareMathOperator{\Var}{Var}
\DeclareMathOperator{\sd}{SD}
\DeclareMathOperator{\Pois}{Pois}
\DeclareMathOperator{\Bin}{Bin}
\DeclareMathOperator{\NegBin}{NegBin}
\DeclareMathOperator{\sech}{sech}


% Text: Calibri, all bold
\setmainfont{Calibri}
\renewcommand{\seriesdefault}{b}

% Math: choose a math font and visually embolden it
\setmathfont{TeX Gyre Termes Math}                  % base math font
\setmathfont[FakeBold=1.9]{TeX Gyre Termes Math}    % embolden; adjust 1.6–2.4

% header
\pagestyle{fancy}
\fancyhf{}
\renewcommand{\headrulewidth}{0pt}   % <-- removes first line

\lhead{\resizebox{!}{1.5cm}{B}} 
\chead{%
  \raisebox{0.2cm}{%
    \shortstack{\Huge Poisson Random Variable}%
  }%
}
\rhead{\resizebox{!}{1.5cm}{B}}

\setlength{\headheight}{1cm}
\setlength{\headsep}{12pt}

\begin{document}
\par\noindent\rule{\linewidth}{1.2pt}\par
\thispagestyle{fancy}

% -------- PAGE 1 --------
\begin{table}[h!]
  \renewcommand{\arraystretch}{1.2}

% -------- Single -------------------
\begin{tabular}{m{1.2in} m{4in}}
\multirow{4}{*}{\fbox{\includegraphics[width=1in]{images/single.png}}} 
&$\lambda = 1$\\
&\\
&\\
&\\
&\\
\end{tabular}
\par\noindent\rule{\linewidth}{1.2pt}\par
% -------- Abstract -------------------
\begin{tabular}{m{1.2in} m{4in}}
\\
\multirow{4}{*}{\fbox{\includegraphics[width=1in]{images/abstract.png}}} 
&$P(X = k) = e^{-\lambda}\frac{\lambda^{k}}{k!}$\\
&\\
&$P(X=0)= e^{-1}\frac{1^0}{0!} = e^{-1} \approx \boxed{0.37}$\\
&\\
&\\
\end{tabular}
\par\noindent\rule{\linewidth}{1.2pt}\par
% -------- Question -------------------
\begin{tabular}{m{1.2in} m{4in}}
\\
\multirow{4}{*}{\fbox{\includegraphics[width=1in]{images/question.png}}} 
&$\lambda = 2$\\
&$t=5$\\
&$\Lambda = \lambda t = 2 \times 5 = 10$\\
&$k=10$\\
\end{tabular}
\end{table}


% second page
\newpage
\thispagestyle{fancy}
\par\noindent\rule{\linewidth}{1.2pt}\par
\begin{table}[h!]
% -------- Answer -------------------
\begin{tabular}{m{1.2in} m{4in}}
\\
\multirow{4}{*}{\fbox{\includegraphics[width=1in]{images/key.png}}} 
&$\lambda = 2$\\
&$t=5$\\
&$\Lambda = \lambda t = 2 \times 5 = 10$\\
&$k=10$\\
&\hrule\\
&\\
&$P(N=10) \;=\; e^{-\Lambda}\,\frac{\Lambda^{10}}{10!}\;=\; e^{-10}\,\frac{10^{10}}{10!}$\\
&\\
&$10! = 3{,}628{,}800$\\
&\\
&$\displaystyle\frac{10^{10}}{10!} = \frac{10\,000\,000\,000}{3\,628\,800}\approx 2{,}755.73$\\
&\\
&$e^{-10}\approx 4.53999\times10^{-5}$\\
&\\
&$P(N=10)\approx 2{,}755.73 \times 4.53999\times10^{-5}\approx \boxed{0.1251}$\\
\end{tabular}
\end{table}
\end{document}