$
\newcommand\tg{\operatorname{tg}}
\newcommand\cotg{\operatorname{cotg}}
\newcommand{\uhel}{{<}\kern-0.5em)\,}
\newcommand\abs[1]{\left| #1 \right|}
\newcommand\zav[1]{\left( #1 \right)}
\newcommand\zavhra[1]{\left[ #1 \right]}
\newcommand\zavslo[1]{\left\{ #1 \right\}}
\newcommand\zavlom[1]{\left< #1 \, \right>}
\newcommand{\podtrzeni}[1]{\underline{ #1 }}
\newcommand{\vysledek}[1]{\underline{\underline{#1}}}
\newcommand{\priume}[4]{
\Bigg\uparrow
\underline{
\begin{array}{rp{2.3cm}r}
#1 & \dots\dots\dots\dots\dots & #2 \\
#3 & \dots\dots\dots\dots\dots & #4
\end{array}}
\Bigg\uparrow}
\newcommand{\nepriume}[4]{
\Bigg\downarrow
\underline{
\begin{array}{rp{2.3cm}r}
#1 & \dots\dots\dots\dots\dots & #2 \\
#3 & \dots\dots\dots\dots\dots & #4
\end{array}}
\Bigg\uparrow}
\newcommand{\nepriumevpravo}[4]{
\Bigg\uparrow
\underline{
\begin{array}{rp{2.3cm}r}
#1 & \dots\dots\dots\dots\dots & #2 \\
#3 & \dots\dots\dots\dots\dots & #4
\end{array}}
\Bigg\downarrow}
$
$ \textbf{Běloun 1.3 b) / str. 7} $
Štítky: výpočty
$ \textbf{Vypočítejte} $
$$ \dfrac{1}{2} + \dfrac{1}{3} \cdot \zav{\dfrac{2}{5}-\dfrac{3}{4}} $$
$ \textbf{Řešení} $
\begin{align*}
&\dfrac{1}{2} + \dfrac{1}{3} \cdot \zav{\dfrac{2}{5}-\dfrac{3}{4}}=\\
=\ &\dfrac{1}{2} + \dfrac{1}{3} \cdot \zav{\dfrac{8-15}{20}}=\\
=\ &\dfrac{1}{2}+\dfrac{1}{3} \cdot \zav{-\dfrac{7}{20}}=\\
=\ &\dfrac{1}{2} - \dfrac{7}{60}=\\
=\ &\dfrac{30-7}{60}=\\
=\ &\vysledek{\dfrac{23}{60}}
\end{align*}
$ \textbf{Výsledek} $
$$ \vysledek{\dfrac{23}{60}} $$
$ \textbf{Konec příkladu} $