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 + 8y = -5.
Ax + By = 3 x + 8y = -5
A(-7) + B (-2) = 3 A x + By = -5
-7A - 2B = 3 The slope of this line = -1/8 = -A/B ....so....1/8 = A /B
-2B = 7A + 3
-2 = (7)(A / B) + 3/B
-2 =7 ( 1/8) + 3/B
-2 = (7/8) + 3/B
- 2 - 7/8 = 3 / B
-23/8 = 3 / B
B = 3 ( 8 / -23) = -24/23
A /B = 1/8
A / ( -24/23) = 1/8
A = (1/8) (-24/23) = -3/23
So
B - A = (-24/23) - (-3/23) = -21 / 23