Find the value of B - A if the graph of Ax + By = 3 passes through the point (-7,2), and is parallel to the graph of x + 3y = -5.

x + 3y = - 5

3y = -x -5

y = -1/3 x - 5/3        slope = - 1/3    parallel slope is the same  - 1/3

 

point slope form

(y-2) = - 1/3 ( x - -7)

y -2 =   - 1/3 x  - 7/3

y  = - 1/3 x  - 1/3               multiply by 3 to get rid of the fractions

 

3 y = -x -1     re-arrange

3y + x  = -1      now multiply by -3

- 9y - 3x = 3        take it from here