 So, let us look at this particular expression. So, the same airship 6000 litre cube operating under same conditions ISA. If the PSP is increased by 49 Pascal's, calculate the Delta N and volume of Ballonet air. So, using the same expression, you will be able to get these two numbers. So, for your ease, I will show you the expressions so that you can use them. So, you can use these expressions. So, Delta N will be equal to minus of Delta PSP P2 minus Delta PSP1 divided by TA plus Delta TSH into K into V. And the Ballonet air weight will be the difference in the PSPs. In fact, you may also be able to use these expressions. Yeah, they are the same. Actually, they are the same expressions because, so now at sea level, we have pressure as 101325 and you increase it by 49 because of super pressure. What is the answer you get? 4.87 minus 35 Newton's and do you get 2.9 meter cubes by finding the volume of the weight and then using the density. Now, let us go to a situation when you are depressurizing the airship. So, now you assume that the PSP is 490 as suddenly it becomes 0. That means you had an airship with the PSP of 490 and then suddenly you got it down to atmospheric pressure. So, there is a reduction of 490. So, now you take Delta PSP as minus 490. So, actually you can do it orally. See, if it is plus 49, it was minus 35 and 2.9. If it is minus 490, it will simply be 350 and 29. So, if you reduce super pressure very quickly, the ballonet has to be filled up with more gas. Ballonet has to be pushed out.