Backpack pocket price

Barbara chose a backpack for school that was three times more expensive than a shoe bag. If the backpack were 30 euros cheaper, it would cost the same as a shoe bag. How many euros did a backpack cost?

Final Answer:

b =  45 Eur

Step-by-step explanation:

$$\begin{gathered} b=3p \\ b-30=p \\ b=3\cdot p \\ b-3p=0 \\ b-p=30 \\ Row2-Row1\to Row2 \\ 2p=30 \\ p=\frac{30}{2}=15 \\ b=0+3p=0+3\cdot 15=45 \\ b=45 \\ p=15 \end{gathered}$$

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