Twenty four men can do a work in 35 days. How many men are required to complete the work in 21 days?  Pick.
A) 39
B) 67
C) 44
D) 40
E) 20
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?