Symbols time!
Infinity:
\infty
$$\infty$$
Fraction:
\frac{}
$$\frac{1}{2}$$
Arrows:
\Leftarrow \Rightarrow \Leftrightarrow
$$\Leftarrow$$ $$\Rightarrow$$ $$\Leftrightarrow$$
Signs for equality:
\approx
$$\approx$$
Finally, the answer box.
\fbox{\begin{minipage}{0.6cm}\hfill\vspace{0.6cm}\end{minipage}}
$$\fbox{\begin{minipage}{0.6cm}\hfill\vspace{0.6cm}\end{minipage}}$$
Example for answer box:
2+2=\fbox{\begin{minipage}{0.2cm}\44\vspace{0.3cm}\end{minipage}}
$$2+2=\fbox{\begin{minipage}{0.2cm}\44\vspace{0.3cm}\end{minipage}}$$
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