A can complete a work in 14 days and B in 28 days. After working together for 5 days, what percentage of work remains? MCQ with Answer and Explanation

Explanation:
Total work = LCM(12, 15, 20) = 60 units. Efficiency of (A+B) = 5, (B+C) = 4, (C+A) = 3. Summing these gives 2*(A+B+C) = 12 => Efficiency of (A+B+C) = 6. Efficiency of A = (A+B+C) - (B+C) = 6 - 4 = 2. Time taken by A alone = 60 / 2 = 30 days.

Explanation:
Remaining work = (1 - 5*(1/18+1/36))×100 = 58.33%.

Explanation:
Let the original number of men be x. Using M1 * D1 = M2 * D2: x * 10 = (x - 5) * 12 => 10x = 12x - 60 => 2x = 60 => x = 30.