graphs

We have the points on the graph  (5,5)  and (20,10)

The slope between these points  is  [ 10 - 5 ] / [ 20 - 5] =   5 / 15  = 1/3

The equation of the line is

y  = (1/3) (x - 5)  + 5      multiply through by 3

3y = x - 5  + 15

3y  = x  + 10    subtract x from both sides

3y  - x   = 10   [first answer ] 

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