This is a working backwards problem. You know he has $35 at the end. Before he gave his brother $5, he would have $40, which is half of what he had before he bought the clothes, so he would have had $80. Before he spent the $40 on shoes, he would have had $120, so the answer is $120.
You see I need to know also the reproduction rate as well to equalize it. If 9% of the population declines each year from 2001 to 2021, around 21,006 would die by 2021. Which is 180% more than the population. If the reproduction rate isn't high enough to beat the declination rates, they'd be extinct by then.
