A, B and C can invidually 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:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e 
days
The number of days taken by A, B, and C to complete the task is 20, 16, and 30 days respectively.
⇒LCM (20, 16, 30) = 240
Let the number of units of work be 240
The number of units works done by A per day = 240 / 20
⇒ 12units
The number of units works done by B per day = 240 / 16
⇒ 15units
The number of units works done by C per day = 240 / 30
⇒ 8units
A & B started working for 4 days, the number of units = 4 × (12 + 15)
⇒ 4 × 27 = 108units
The remaining task = 240 - 108 = 132
Number of days by C to complete the task = 132 / 8
⇒ 16.5 days or days