Twenty four men can do a work in 35 days. How many men are required to complete the work in 21 days? Choose the correct choice from the following answers:
A) 20
B) 10
C) 50
D) 40
E) 60
40   40   We have M1 401 = M2 402   So, 24 * 35 = M2 * 21 =&gt; M2 = 40.
<result>D</result>
Twenty four men can do a work in 35 days. How many men are required to complete the work in 21 days?