A and B together can do a work in 9 days. If A alone can do it in 18 days. In how many days can B alone do it?	Pick one.
A) 10 B) 99 C) 18 D) 55 E) 21
1/9 – 1/18 = 1/18   =&gt; 18   Answer: 18
<result>C</result>
A and B together can do a work in 9 days. If A alone can do it in 18 days. In how many days can B alone do it?