17. (10 points) A store purchased a batch of toys, and the profit from selling 30 toys at a retail price of 12 yuan each is the same as the profit from selling 20 toys at a retail price of 15 yuan each. What is the purchase price of each toy in yuan?
【Solution】Solve: $(12 \times 30-15 \times 20) \div(30-20)$,
$$
\begin{array}{l}
=(360-300) \div 10, \\
=60 \div 10, \\
=6 \text { (yuan); }
\end{array}
$$

Answer: The purchase price of each toy is 6 yuan.