Jack's plumbing charges customers $100 per hour for repair jobs. A-1 Plumbing chargers according to the equation y= 75x + 50, where x = time in hours and y = cost in dollars . Explain why A-1 plumbing charges less than jacks plumbing for a 4-hour repair job . Does A-1 plumbing charge less than jacks plumbing for all repairs jobs ?