D is a function  because  there are no repeated x values 
for example b is not a function because we have (0,-7) and (0,-9)
        
             
        
        
        
Each classroom donated around 320 cans(or more) of food. 
320x28=8,960.
        
                    
             
        
        
        
In this case, the best way to work this out is to find what 1cm is equal to. In this case, you have to divide 51/3, giving you 17. You know that 17 feet. You can now divide 187/17, giving you 11.
Therefore, 11cm is equal to 187 feet.
Hope this helps
        
                    
             
        
        
        
Please, group your sets of numbers, using {   }  notation or at least semicolons ( ; ).  Thanks.
Looking at what I think is your first set:   { sqrt(4), sqrt(5), sqrt(16) }
Square each of these and then subst. the results into the Pythagorean Theorem:
  { 4, 5, 16 }        Do 4 and 5 when added together result in 16?  NO.
Therefore,   { sqrt(4), sqrt(5), sqrt(16) }  does not produce a right triangle.
Your turn.  Pick out the next 3 numbers and test them using the Pyth. Thm.