Compute npv until it becomes positive for best bidder

Question

3 bidders for the satellite system have given offers:

Bidder A

First payment:                   $100m at the start

Second Payment:              $250m at the beginning of second year

Third payment:                  $250m at the end of third year

Final payment:                   $400m on completion at the end of 4^th year.

Bidder B

First payment:                   $ 200m at the start

Second Payment:              $ 250m at the end of second year

Third payment:                  $ 250m at the end of third year

Final payment:                   $ 300m on completion at the end of 4^th year.

Bidder C

First payment:                   No payment at start

Second Payment:              $300m at the beginning of second year

Third payment:                  $200m at the beginning of third year

Final payment:                   $500m on completion at the end of 4^th year.

All 3 bidders have been analyzed to be technically compliant.

i) Suppose 8% discount +inflation rate, which bidder will you suggest to the management?

b) Annual operations and maintenance after completion is evaluated to be $40 million, payable at the end of year and with 5% annual increase thereafter.

Customer has committed to pay $250 million annually at the end of every year after completion, with first payment at the end of fifth year from start and with 5% annual increase thereafter. Discount + inflation rate is still 8%. For best bidder, compute NPV until it becomes positive.