Answer and Explanation:
Computation:
               Cost-to-cost method          Â
Year    Cost     cost(%)   Revenue    Income  Â
2016 Â $202,500 30% Â Â Â Â $270,000 Â Â Â $67,500
2017 Â $337,500 50% Â Â Â Â $450,000 Â Â Â $112,500
2018 Â $135,000 20% Â Â Â Â $180,000 Â Â Â $45,000 Â Â
Total  $675,000   100%    $900,000    $225,000
Cost % = Cost of particular year / Total cost
Revenue:
Year 2016 =$900,000 × 30% = $270,000
Year 2017 = $900,000 × 50% = $450,000
Year 2018 = $900,000 × 20% = $180,000.
Income:
= Revenue - Cost
 Year 2016 = $270,000 - $202,500
Year 2017 = $450,000 Â - $337,500
Year 2018 = $180,000 - $135,000