Question

A, B andC can do a piece of work in 12,15 and 20 days respectively .How long they take to do it working together ​

Answer 1

Answer:

Explanation:

Let that work be x

Working speed of A = 12/x

Working speed of B = 15/x

Working speed of C = 20/x

Working speed of everyone is

$\frac{x}{12} +\frac{x}{15} +\frac{x}{20}$

$\frac{5x+4x+3x}{60} \\=\frac{12x}{60} \\=\frac{5x}{1}$

It means that they can together do the same work 5 times in a day or they can finish the work together in just 4.8hours.