Cris can encode a set of records in 6 days, and Dan can do it in 12 days. Working together, how many days will they take?
Correct answer: B. 4 days
Cris does 1/6 of the job a day and Dan 1/12. Together they do 1/6 + 1/12 = 2/12 + 1/12 = 3/12 = 1/4 of the job a day, so they finish in 4 days.
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