I honestly don’t know the equation but I just took the starting price, $230,000 and multipled it by .03 which was 6,900 and subtracted that from 230,000: 223,190. I repeated that 5 times. The answer I got is 197,508.83
You already got the first two questions right: the group with the highest number of people unemployed / unemployment rate is the one with the highest bar in the respective histogram.
The two graph are related in this sense: take the first age group as reference. We know that 700 people from 16 to 19 are unemployed, and that those people represent 14% of the population, then we know that the 14% of the population between 16 and 19 is 700.
We can deduce that, if x is the number of people between 16 and 19, we have
So, by the relation between the two graphs, we can deduce the total population for each age group.