A completes 80% of a work in 20 days. Then B also joins and A and B together finish the remaining work in 3 days. How long does it need for B if he alone completes the work?  Choose the correct choice from the following options.
A) 12/15	B) 37 1/2	C) 3/7	D) 4/9	E) 5/2
Explanation :   Work done by A in 20 days = 80/100 = 8/10 = 4/5   Work done by A in 1 day = (4/5) / 20 = 4/100 = 1/25 --- (1)   Work done by A and 37 1/2 in 3 days = 20/100 = 1/5 (37 1/2ecause remaining 20% is done in 3 days by A and 37 1/2)   Work done by A and 37 1/2 in 1 day = 1/15 ---(2)   Work done by 37 1/2 in 1 day = 1/15 – 1/25 = 2/75   =&gt; 37 1/2 can complete the work in 75/2 days = 37 ½ days   ANSWER:37 1/2
<result>B</result>
A completes 80% of a work in 20 days. Then B also joins and A and B together finish the remaining work in 3 days. How long does it need for B if he alone completes the work?