If some information is missing, you can have assumptions. Just make sure that your assumptions will be mentioned on the answer

Assuming that Company A will generate 3M RECs in the offshore operation. Considering that the company's own consumption is 300,000 RECs/a will be used for the operation in Australia, 2,7MRECs/a will remain to be sold in the Australian market.

Assuming that in 2020 REC's price is $40 and in 2040 will be $50.

Draw demand curve in Australian dollars i.e., use exchange rate, price level/interest rate information. In addition, describe in words what is drawn. Then, Calculate the price elasticity of demand and explain what this means here.