Question

a can do a piece of work in 4 days. b can do it in 5 days. with the assistance of c they completed the work in 2 days. find in how many days can c alone do it? 20 30 25 18 next ques

Answer 1

20 will be the answer

Answer 2

in this problem we solve very easy method

by using lcm method

A = 4

B = 5

lcm of , 4 , 5 = 20 unit

suppose 20 unit is total work

A and B separate do one days work is

20/4 = 5 unit

and

20/5 = 4 unit

sum = 5 + 4 = 9 unit together one days

in two days.

9 × 2 = 18 unit

remaining work = 20 - 18 = 2 unit

it can do C in 2 day's

means 1 days = 1 unit

total work ÷ 1

20/1 = 20 days

Ans = 20 days of C