A can do a job in 5 days and B can do it in 15 days. A and B working together will finish twice the amount of work in ------- days?  Answers
A) 21 ½ days	B) 22 ½ days	C) 23 ½ days	D) 12 ½ days	E) 7 ½ days
7 ½ daysxplanation:   1/5 + 1/15 = 4/15 = 4/15   15/4 = 15/4 *2 = 7 ½ days   Answer: 7 ½ days
<result>E</result>
A can do a job in 5 days and B can do it in 15 days. A and B working together will finish twice the amount of work in ------- days?