1 womans 1 days work =$ \dfrac{1}{70} $

1 childs 1 days work =$ \dfrac{1}{140} $

$\left(5 women + 10 children\right)$s days work =$ \left(\dfrac{5}{70} +\dfrac{10}{140} \right) $=$ \left(\dfrac{1}{14} +\dfrac{1}{14} \right) $=$ \dfrac{1}{7} $

$\therefore$ 5 women and 10 children will complete the work in 7 days.