Comparing 7/10 and 1/3 by first comparing both to 1/2,
[tex]\begin{gathered} Step\text{ 1: }\frac{7}{10}\text{ is less than }\frac{1}{2} \\ \frac{7}{10}=0.7\text{ and }\frac{1}{2}=0.5 \\ 0.7\text{ is not less than 0.5 } \\ \text{Step 1 is wrong.} \end{gathered}[/tex]
Hence, the first mistake was in Step 1
