Answer:
-a/b
Explanation:
ax+by=c
First get the equation in slope intercept form ( y= mx+b where m is the slope and b is the y intercept)
Subtract ax from each side
ax+by -ax=-ax +c
by = -ax+c
Divide each side by b
by/b = -ax/b + c/b
y = -a/b * x + c/b
The slope is -a/b and the y intercept is c/b
We want the line parallel so it has the same slope, -a/b