D1 = 60 for a price of $80. Charging $80 will ensure supply exceeds demand.
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The store apparently could charge a price slightly lower than $80, but we cannot tell from the chart how much lower.
70 pieces
7/10 = x/100
10*10=100
7*10 = 70
70/100
First you want to change the fraction into a decimal on this one the decimal is going to be .3333 now your problem looks like 8-.3333x=16 now subtract the 8 and you get -.3333x=16 now divide by -.3333 and you get -48