($\frac{1}{3}$ + $\frac{3}{4}$ - $\frac{13}{12}$) : ($\frac{12}{23}$ + $\frac{123}{234}$ + $\frac{1234}{2345}$)
= ($\frac{4}{12}$ + $\frac{9}{12}$ - $\frac{13}{12}$) : ($\frac{12}{23}$ + $\frac{123}{234}$ + $\frac{1234}{2345}$)
= 0 : ($\frac{12}{23}$ + $\frac{123}{234}$ + $\frac{1234}{2345}$)
= 0