Question

for doing a certain work the ratio of efficiency of a and b is 7: 11. C alone can do the same work in 84 days working together A and B can do the same work in 38 1/2 days. b and c together will complete the same work in ?
1)30 days
2) 36 days
3) 40 days
4) 42 days ​

Answer 1

hope iy will help u

answer is 11 days

but acc to ques and options answer is 30 days

thi answer is only for understanding