Question 634110
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Hi,
Using the standard slope-intercept form for an equation of a line y = mx + b
  where m is the slope and b the y-intercept.
line that passes through the point (2,4) and has the indicated slope m =  -1.   

Line
 y = (-1)x + b
 4 = (-1)·2 + b   |Using ordered pair (x,y):(2,4)  to solve for b
 6 = b
 y = -x + 6        or x + y = 6