Seller 3

A seller wanted to sell 100 cheaper and 50 more expensive mobile phones. The price difference between a cheaper and a more expensive mobile is 30 euros. Originally he wanted to sell each cheaper one at a 20% discount and each more expensive one at a 12% discount. In the end he decided to sell the cheaper ones at a 40% discount and the more expensive ones at the original price, whereby his revenue from the sale of all mobiles fell by 8% compared to the original plan. How much did a cheaper mobile cost on sale with a 40% discount?

Final Answer:

x =  42 Eur

Step-by-step explanation:

$$\begin{gathered} 100a+50b \\ b=30+a \\ 100a+50(30+a) \\ r=100\%-8\%=1-\frac{8}{100}=0.92 \\ r\cdot (0.80\cdot 100a+0.88\cdot 50(30+a))=0.60\cdot 100a+50(30+a) \\ 0.92\cdot (0.80\cdot 100a+0.88\cdot 50(30+a))=0.60\cdot 100a+50(30+a) \\ 0.92\cdot (0.80\cdot 100\cdot a+0.88\cdot 50\cdot (30+a))=0.60\cdot 100\cdot a+50\cdot (30+a) \\ 4.08a=285.6 \\ a=\frac{285.6}{4.08}=70 \\ a=70 \\ b=30+a=30+70=100\text{eur} \\ x=0.60\cdot a=0.60\cdot 70=42\text{Eur} \end{gathered}$$

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