Question

8 men can finish a job in 21 days. If 4 more men join them, then in how many days the work will be completed ?​

Answer 1

there's a special formula for these type of questions...

m1 × d1 = m2 × d2

8×21 = 12 × d2 (8+4 = 12)

8×21/12 = d2

14 = d2

so, it will take 14 days to complete work if 4 more men are added.