Question 1019664
12 people paint a house in 5 days. Therefore, 60 people paint a house in a day, and a person's rate is
 
{{{(1/60)(house/day)}}}

In 3 days, one person can paint 

{{{(3/60)(house/day)}}}  (i.e. 1/20 house)

Therefore we need 60/3 people or 20 to paint 1 house in 3 days.