Question

A can do a piece of work in 80 days. he works for 10 days and then B alone finishes the work in 42 days. the together could do the work in how many days?
A- 24 days B-25 days C- 30 days D- 35 days
​(explain with proper steps)

Answer 1

Let the average work by taking lcm of total days
lcm=1470
A can do the work in 1 day =1470/80
=21 work
B can do the work in 1 day =1470/42
=40 work
Both of them can do the work in 1 day =40+21
=61 work 
total work is 1470 so,
divide it by 61 
answer will be 24.something