Let the original value be x.
After the first year, the value will decrease 50%, so, it will be 0.5x.
By the end of the second year, it will decrease other 8%, 0.08.
so:
0.5x*(1-0.08) = 0.46x
And by the end of the third year, will decrease 8% again, so:
0.46*(1-0.08) = 0.4232x
The price will be 42.32% of the original value.