15-23 For the following projects what is the opportunity cost of capital if the budget is (a) $60,000, and (b) $120,000? If Project 4 has an external environmental cost of $1000 annually that is included, (c) how does this change the answer to (a)? (d) How does this change the answer to (b)? G Project Life (years) First Cost Annual Benefit Salvage Value 1 20 $20,000 $4000 2 20 20,000 3200 $20,000 3 30 20.000 3300 10,000 4 15 20,000 4500 5 25 20,000 4500 -20,000 6 10 20,000 5800 7 15 20,000 4000 10,000