Ali can finish a piece of work in 12 days and Bilal in 18 days. In how many days can they finish it together?
Correct answer: B. 7.2 days
Take the work as 36 units (LCM of 12 and 18): Ali does 3 units a day and Bilal 2, so together 5 a day; 36 ÷ 5 = 7.2 days.
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