$x + 7\frac{4}{15} = 9\frac{7}{10}$
$x = 9\frac{21}{30} - 7\frac{8}{30}$
$x = 2\frac{12}{30}$

$8\frac{9}{14} - x = 4\frac{3}{7}$
$x = 8\frac{9}{14} - 4\frac{6}{14}$
$x = 4\frac{3}{14}$

$x - 3\frac{8}{9} = 5\frac{1}{12}$
$x = 5\frac{3}{36} + 3\frac{32}{36}$
$x = 8\frac{35}{36}$