Find the equation of the line
a) parallel to the line y = 2x + 4, passing through the point (6,2)
b) parallel to the line x + 2y = 5, passing through the point (2,-5)
c) perpendicular to the line 2x + 3y = 12, passing through the point (7,3)
d) perpendicular to the line 4x - y = 6, passing through the point (4,-1)