$\frac{7}{11} + х = \frac{10}{11}$
$x = \frac{10}{11} - \frac{7}{11} = \frac{3}{11}$

$x + \frac{7}{10} = 1\frac{2}{10}$
$x = 1\frac{2}{10} - \frac{7}{10} = \frac{12}{10} - \frac{7}{10} = \frac{5}{10}$