A, B and C can individually complete a task in 20 days, 16 days and 30 days, respectively. If A and B started working on the task, and they worked for 4 days and left, then the number of days required by C to finish the remaining task is:

$16 \frac{1}{2}$ days

A = 20 days, B = 16 days, C = 30 days,

⇒ A + B worked for 4 days = (12 + 15) x 4 = 108 units. ..(Efficiency × Days = Total work)

⇒ Remaining work = 240 - 108 = 132 units,

⇒ Time required by C to complete 132 units = \(\frac{132}{8}\) = \( { 16}_{2 }^{ 1} \) days.      ..(\(\frac{Work}{Efficiency}\) = Time)