Answer:
the 11th week.
Explanation:
the expression for the markdown on the 8th week is p-.15p=.85p since it will get marked down 15% on the 8th week. the expression for the additional markdowns is p-.05p=.95p since it will get marked down an additional 5% every week after the 8th week.
On the 8th week it will be marked down to .85(150) = 126.50.
9th week: .95(127.50) = 121.13
10th week: .95(121.13) = 115.07
11th week: .95(115.07) = 109.32
109 is under 110 therefore it is the 11th week.