Determine whether the lines are parallel, perpendicular, or neither.
a. y = 5x − 2 and y = 10x − 4
b. y = -2x − 6 and 2y + 4x = 12
c. y = 10x − 2 and y + 10x = 0
d. 4y + 3x = -18 and 3y = 4x + 7.
e. 5y = 7x + 2 and y = fx + 12