A company has 8 grade one and 10 grade two inspectors for quality control inspection. At least 1,800 pieces must be inspected in an 8-hour day. Grade one inspector can check 25 pieces an hour with an accuracy of 98%. Grade two inspectors can check 15 pieces an hour with an accuracy of 95%. The wage rate of grade one inspectors is birr 4 per hour, while grade two inspectors are birr 3 per hour. Any error made by an inspector costs birr 2 to the company.  Solve the LPP