Answer:  12 hours
Step-by-step explanation:
Given : Working together, it takes Sam, Jenna, and Francisco two hours to paint one room.
When Sam works alone, he can paint one room in 6 hours. When Jenna works alone, she can paint one room in 4 hours. 
Let 't' be the time taken by Francisco to paint one room on his own.
Then , we have
Rate of work of  Sam +Rate of work of Jenna + Rate of work of  Francisco =Rate of work they all do together
 
i.e.  
i.e.  
i.e.  
i.e.  
i.e.  
i.e.  
i.e. t= 12
Hence,  Francisco would take 12 hours to  paint one room on his own.
 
        
             
        
        
        
-32/40 + -35/40 = -32+-35/40
= -67/40
= -1.675
The answer would then be -1.675.
        
             
        
        
        
Let
 The origin of coordinates the tree
 r1 = vector position of the child 1.
 r2 = vector position of the child 2
 Child 1:
 r1 = (12i + 12j)
 Child 2:
 r2 = (-18i + 11j)
 The scalar product will be given by:
 r1.r2 = ((12) * (- 18)) + ((12) * (11)) = - 84
 The scalar product of their net displacements from the tree is -84m ^ 2
        
             
        
        
        
Answer:
If he has 45% of his cheak remaining we already have the remaining so we just to turn it into a fraction 
First we put it over 100
<u>45</u>
100
Then we reduce it to the lowest terms
which would be
9/20