The designer of a penstock for a small hydroelectric cogeneration station has two options: using steel pipe, which costs $150,000 installed and requires $5000 yearly for painting and leak-detection maintenance or Heavy duty plastic pipe DSR4.3 which costs $180,000 and requires $1200 yearly for leak-detection maintenance. Both options have an expected life of 25 years. If the interest rate is 8%, which choice has the lower present equivalent cost and how much lower is this present equivalent cost