A can do a piece of work in 12 days and B can do it in 30 days. They work on alternate days; starting with A. In how many days will the work be completed?

$16\frac{4}{5}$

A = 12 days, B = 30 days,

⇒ They work on alternate days, starting with A,

 1st day = 5 units,

 2nd day = 2 units,

Every 2 days, 7 units of work is completed,

So, in 16 days, 56 units of work is completed,

Therefore, in \( { 16}_{ 5}^{4 } \) days, total work is completed.