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\documentclass{scrreprt}
\usepackage{amsmath}
\begin{document}
\begin{multline*}
x = \frac{a+b+c+d+e+f+g+h+j+k+l+m+n+o+p+}{a}\\\frac{+q+r+s+t+u+v+w+x+y+z}{a}
\end{multline*}
 \end{document}