y = mx+b
where m is the slope and b is the y-intercept.
The three equations with a y-intercept of –5 would be as follows:
y = 8x - 5
y = 3x - 5
y = -7x -5
Any 3 values of m will do, so pick m=-1, 0 and 1:
y-3=-x-2 which is the same as y=-x+1
y-3=0 same as y=3 (this is a horizontal line at y=3 for all values of x)
y-3=x+2 same as y=x+5
They all intersect at the given point.