what am I doing wrong?  
" write an equation of each line passing through the given pointers.  give answers in standard form"
a) (-1,2) and (5,7)
the answer is 5x-6y=-17
I just cant figure out where the negative in the 17 comes from.  aside from that I have the right numbers.
thank you!
                                             
                                          
                                          
                                        
											