A does 4/5th of a work in 20 days. He then calls in B and they together finish the remaining work in 3 days. How long B alone would take to do the whole work?
Choose the correct choice from the following:  A) 23 days  B) 37 days  C) 37 ½ days  D) 40 days  E) 41 days
Explanation:   A can finish the whole work in 20 × 5/4 days = 25 days   A and B together finish the whole work in 5 × 3 days = 15 days   Therefore, B can finish the whole work in 25 B/ 25 + B = 15   25 B = 15 ( 25 + B)= 375 + 15B   10B = 375 and B = 375/10 = 37 ½ days.   Answer: Option 37 ½ days
<result>C</result>
A does 4/5th of a work in 20 days. He then calls in B and they together finish the remaining work in 3 days. How long B alone would take to do the whole work?