1.
$\begin{align*}
{{15x}\over{8}}+{{4}\over{3}} &= {{7x}\over{4}}+{{13}\over{8}} && |\cdot 24\\
45x+32 &= 42x+39 && |-\left(42x+32\right)\\
3x &= 7 && |:3\\
x &= {{7}\over{3}}
\end{align*}$
2.
$\begin{align*}
{{19x}\over{20}}+{{6}\over{5}} &= {{4x}\over{5}}+{{7}\over{5}} && |\cdot 20\\
19x+24 &= 16x+28 && |-\left(16x+24\right)\\
3x &= 4 && |:3\\
x &= {{4}\over{3}}
\end{align*}$
3.
$\begin{align*}
{{53x}\over{18}}+{{7}\over{6}} &= {{8x}\over{3}}+{{4}\over{3}} && |\cdot 18\\
53x+21 &= 48x+24 && |-\left(48x+21\right)\\
5x &= 3 && |:5\\
x &= {{3}\over{5}}
\end{align*}$