1 уравнение
А 2 расчет

$0.5x+2 frac{1}{2} x-0.68=1.72$
$0.5x+(2 +0.5) x=1.72+0.68$
$0.5x+2.5 x=2.4$
$3x=2.4$
x=2.4:3
x=0.8

2) $4 frac{1}{6} *0.6+6 frac{2}{5}:1 frac{1}{7} -6.7= frac{4*6+1}{6} * frac{6}{10} + frac{6*5+2}{5}: frac{1*7+1}{7} -6 frac{7}{10}$ $= frac{25}{10} + frac{32}{5}* frac{7}{8} -frac{67}{10} =frac{25}{10} + frac{56}{10} -frac{67}{10}= frac{25+56-67}{10} = frac{14}{10} = frac{7}{5}$