on question 1, year 1 inflation index is 100 reducing to 90 in year 2, how can you the % , I don’t know where I am going wrong?
To calculate the difference between year 0 and year 2, take original figure (100) and subtract year 2 figure (90). That gives you a difference of 10. Divide that by the original number (100) and multiply by 100. So in this case, the percentage decrease is 10%.