solve clearly and neat with complete explanation steps

The total quantity of natural resources to be extracted is 200 units, the nancial rate of return is 15% pa, the population growth rate is 30% pa, the price now is $60 per unit, the price in 1 year is $80 per unit and the marginal extraction cost now and in 1 year is $40 per unit and $50 per unit respectively. How many units should be extracted now? Which factors, i.e. external and internal, do you think are important in your estimation for the output