Question

A AND B CAN DO A WORK IN 10 DAYS, B AND C CAN DO THAT WORK IN 15 DAYS . C AND A CAN DO THAT WORK IN 20 DAYS. SO FIND HOW MANY DAYS WILL C ALONE TAKE TO DO THAT WORK​

Answer 1

B's 5 days work =101×5 =21

Remaining work =1−21 =21

c can finish work =15×21 =7.5 days

Answer 2

(a+b) x 10 = (b+c) x 15= (c+a) x 20 = work=60 units

a+b= 1/10 work= 6 units

b+c=1/15 work=4 units

c+a=1/20 work =3units

2a+2b+2c=13 units

a+b+c=6.5 units

c=6.5-6=0.5units

number of c days= 60/0.5=120

120 days? That doesn't seem right.