



 
Hi Anni, Suppose the cost is $C$ dollars, the total cost is $TC$ dollars and the selling price is $SP$ dollars. Since the total cost= cost + commission (15% of selling price) we have \[TC = C + 0.15 \times SP \mbox{ dollars.}\] Since the selling price is the total cost plus a 24% margin we also have that \[SP = TC + 0.24 \times TC = 1.24 \times TC \mbox{ dollars.}\] Substituting this expression for $SP$ into the first equation yields \[TC = C + 0.15\times 1.24 \times TC = C + 0.186 \times TC \mbox{ dollars.}\] Hence \[TC  0.186 \times TC = 0.814 \times TC = C \mbox{ dollars.}\] or \[TC = \frac{C}{0.814} \mbox{ dollars.}\] Since $SP = 1.24 \times TC \mbox{ dollars.}$ we finally get \[SP = \frac{1.24}{0.814} \times C = 1.52 \times C \mbox{ dollars.}\] Let me know if I have misread your question, 



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