A can finish a piece of work in 12 days. B can do it in 20 days. They work together for 9 days and then A goes away. In how many days will B finish the work?
Pick one:
A) 6 days
B) 4 days
C) 5 days
D) 3 days
E) 7 days
9/12+ (9 + x)/20 = 1 =&gt; x = 5 days   Answer: 5 days
<result>C</result>
A can finish a piece of work in 12 days. B can do it in 20 days. They work together for 9 days and then A goes away. In how many days will B finish the work?