Question

If 4 workers can make 42 toys in 6 days. How many toys can 12 workers make in 3 days.

Answer 1

Given that, $4$ workers, $42$ toys, $6$ days
that means those same

$4$ workers can make $21$ toys in $3$ days. ($1/2$ the time, so $1/2$ the toys.)
$12$ workers is three sets of $4$ workers.

so,
$12$ workers can make $3\left(21\right)=63$ toys in $3$ days.

Hence, this is the answer.