20 workers can finish a work in 30 days. After how many days should 5 workers leave the job so the work is completed in 35 days? Choose the correct answer:
A) 7	B) 6	C) 15	D) 4	E) 3

Rationale: work done by 15 workers in 35 days = 15 * 35 = 525 men days . now , work remaining = 600 – 525 = 75 men days and we have 5 workers . so 5 workers will work for 75 / 5 = 15 days . answer : c
Answer: C