a) $x$ x $\frac{2}{5}$ = $\frac{4}{7}$ 

$x$ = $\frac{4}{7}$ : $\frac{2}{5}$

$x$ = $\frac{4}{7}$ x $\frac{5}{2}$

$x$ =  $\frac{10}{7}$

b) $x$ : $\frac{6}{11}$ = $\frac{44}{9}$

$x$ = $\frac{44}{9}$ x $\frac{6}{11}$

$x$ = $\frac{264}{99}$