What is the present value of a stream of cashflows that are $1.5 billion in year 1,$2.1 billion in year 2 , and $1.9 billion in year 3 . Assume the discount rate is 7% ? $4.79 billion $4.12 billion $5.05 billion $3.90 billion $3.74 billion $4.45 billion $5.81 billion