Question

A is twice more efficient than B and he can complete the work $12$ days carlier than B. In what time can B complete the work?

Answer 1

Let B take $x$ days, then A takes $x-12$ days, but A is twice efficient than B, hence A will take half the time taken by B.
Hence, $(x-12)=\frac{1}{2}x$
$\therefore 2x-24=x$
$\therefore 2x-x=24$
$x=24$ days