[tex](5 \frac{1}{2} -4 \frac{1}{3} )* \frac{6}{7} = \\
=( \frac{5*1+2}{2} - \frac{4*1+3}{3} )* \frac{6}{7}
\\ =( \frac{7}{2} - \frac{7}{3} )* \frac{6}{7}
\\ =( \frac{7*3}{2*3} - \frac{7*2}{3*2} )* \frac{6}{7}
\\ =( \frac{21}{6} - \frac{14}{6} )* \frac{6}{7}
\\ = \frac{7}{6} * \frac{6}{7}
\\ = \frac{1}{1} =1[/tex]