Question

a and b do a work in 30 days while b and c do it in 24 days and c and a do it in 20 days how many days will a take to complete the whole work

Answer 1

one days work of :

a+b = 1/30

b+c = 1/24

c+a = 1/20

then

2a+2b+2c = 1/30 +1/24+ 1/20 = 1/8

a+b+c = 1/16

a = a+b+c -a

= 1/16 - 1/24

= 1/48

a alone can finish the work in 48days