+26388 12 1\2+8 1\6+9 1\3=?
1) 20 2) 30
3) 40 4)50
\(\begin{array}{|rcll|} \hline && 12 \frac 1 2 +8 \frac 1 6 +9 \frac 1 3 \\ &=& 12 + \frac 1 2 +8 + \frac 1 6 +9 + \frac 1 3 \\ &=& 12 + 8 + 9 + \frac 1 2 + \frac 1 6 + \frac 1 3 \\ &=& 29 + \frac 1 2 + \frac 1 6 + \frac 1 3 \\ &=& 29 + \frac{ 1 } { 2 }\cdot \frac{ 3 } { 3 } + \frac 1 6 + \frac {1}{ 3} \cdot \frac{ 2 } { 2 }\\ &=& 29 + \frac{ 3 } { 6 } + \frac 1 6 + \frac {2}{ 6}\\ &=& 29 + \frac{ 3+1+2 } { 6 } \\ &=& 29 + \frac{ 6 } { 6 } \\ &=& 29 + 1 \\ &=& 30 \\ && \mathbf{12 \frac 1 2 +8 \frac 1 6 +9 \frac 1 3 = 30} \\ \hline \end{array} \)
