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.
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We have Ax + By = 3 (1)
If this passes through (7, -2) then 7A - 2B = 3 (2)
We can rearrange equation (1) in the form y = -(A/B)x + 3/B The slope of this equation is -A/B
The equation x + 3y = -5 can be rearranged as y = -(1/3)x -5/3 the slope of which is -1/3
For the two lines to be parallel the slopes must be the same, hence -A/B = -1/3 (3)
Now you have two equations ((2) and (3)) that can be solved for A and B.
Can you take it from here?