Question
What is wrong in the following additions?
$\begin{array}{r}8 \frac{1}{2}=8 \frac{2}{4} \\ +4 \frac{1}{4}=4 \frac{1}{4} \\ \hline=12 \frac{3}{8} \\ \hline\end{array}$
$\begin{array}{r}8 \frac{1}{2}=8 \frac{2}{4} \\ +4 \frac{1}{4}=4 \frac{1}{4} \\ \hline=12 \frac{3}{8} \\ \hline\end{array}$

