$1/2*12/13+1/3*12/13+1/4*12/13$
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MathBot Answer:
\[\frac{\frac{1}{2} \cdot 12}{13} + \frac{\frac{1}{3} \cdot 12}{13} + \frac{\frac{1}{4} \cdot 12}{13} = 1\]
\[\begin{aligned}\frac{\frac{1}{2} \cdot 12}{13} + \frac{\frac{1}{3} \cdot 12}{13} + \frac{\frac{1}{4} \cdot 12}{13}& = \frac{12}{2} \cdot \frac{1}{13} + \frac{12}{3} \cdot \frac{1}{13} + \frac{12}{4} \cdot \frac{1}{13}\\& = \frac{1}{2} \cdot \frac{12}{13} + \frac{12}{3} \cdot \frac{1}{13} + \frac{12}{4} \cdot \frac{1}{13}\\& = \frac{6}{13} + \frac{12}{3} \cdot \frac{1}{13} + \frac{12}{4} \cdot \frac{1}{13}\\& = \frac{6}{13} + \frac{1}{3} \cdot \frac{12}{13} + \frac{12}{4} \cdot \frac{1}{13}\\& = \frac{6}{13} + \frac{4}{13} + \frac{12}{4} \cdot \frac{1}{13}\\& = \frac{6}{13} + \frac{4}{13} + \frac{1}{4} \cdot \frac{12}{13}\\& = \frac{6}{13} + \frac{4}{13} + \frac{3}{13}\\& = \frac{10}{13} + \frac{3}{13}\\& = 1\end{aligned}\]