OK sup man. 50% is spent on the crystal vase, leaving with 50%.
SO 20% of the remaining money is spent on a hat, leaving $640
(80%).
so for part a, they are asking the percentage of the original
sum spent on the hat. SO $640/8=$80 (10%). then 80 multiply
by 2 = 160$. DONE.
for part b, the percentage of money left would be 80 multiply by
10 would be 800$ (50% of the ORIGINAL SUM). so then you multiply by
2 to get the original sum (1600$). therefore, 640/1600 multiply by
100 = 40%.
part c (ans is above)
hope this helps man