Y = 3bx - 7x
y = x(3b - 7)
Divide each side by 3b - 7 (assume that it is not zero).

Answer:
X=6 would be a vertical line on the 6 dash on the x-axis
A vertical line has no slope so the equation of the line is simply x = constant.
For this question we have:
x = 2
as the equation of the line.
Answer: x = 2