Question 1054311

12 Workers can finish a third of a house in 15 days. How many workers must be added to finish the rest of the house in the next 18 days? 

Could you please explain and draw some diagrams or pictures which could help me understand? Thanks. (Or anything that would help me in solving unit rate problems)
<pre>{{{highlight_green(matrix(1,2, 8, more))}}}