Angela, Bernie, and Colleen can complete a job, all working together, in 3 hours. Angela and Bernie, working together at their respective rates, can complete the same job in 4 hours. How long would it take Colleen, working alone, to complete the entire job?
Choices:
A) 8 hours  B) 10 hours  C) 12 hours  D) 16 hours  E) 20 hours
A+B+C complete the job in 3 hours.   A+B complete the job in 4 hours.   A+B and C complete the job in 3 hours --&gt;1/(A+B) + 1/C = 1/3--&gt;1/4+1/C=1/3 ----&gt; C=12 hours. ANS 12 hours
<result>C</result>
Angela, Bernie, and Colleen can complete a job, all working together, in 3 hours. Angela and Bernie, working together at their respective rates, can complete the same job in 4 hours. How long would it take Colleen, working alone, to complete the entire job?