 For question one, we want to find out how much the emissions will be reduced if we reduce our use of coal compared to control case where we're not changing anything as time goes on. So to begin, just run the model as it is when you first open it and we're looking at graph page one, which is going to show us the total carbon emissions over time. And then we run along here until we get to the year 2100 and we see about 29.6 something, let's say, 29.6. Now we make the change and to do that, first we flip the coal switch on. We change the coal reduction time from 30 to 20 and we change the fraction of coal reduction to 0.24 and just type that in there. So this nearly gets rid of all of our use of coal in terms of the sources of energy that we use. Now we can run the model again and then we compare the emissions in the year 2100. So we see we have about something like 18.3 in this scenario. So we just subtract that from the 29.6 that we got, let's see, it was about 29.6 in the year 2100 there. And the difference is 11.3 gigatons of carbon and that's the answer to the problem.