a and b can do a piece of work in 48 days , a and c can do it in 60 days , b and c can do it 72 days . in what time can c alone do it ?
explanation : ( a + b ) 1 day work = 1 / 48 ( b + c ) 1 day work = 1 / 72 ( a + c ) 1 day work = 1 / 60 by adding 2 ( a + b + c ) = 1 / 48 + 1 / 72 + 1 / 60 = 37 / 720 ( a + b + c ) 1 day work = 37 / 1440 a 1 day work = 37 / 1440 – 1 / 72 = 17 / 1440 = 85 days ( approximately ) answer : option c
add(subtract(72, 48), 60)