8. (3 points) For a certain product, if the purchase price decreases by 10%, and the selling price remains unchanged, then the gross profit margin (Gross Profit Margin = $\frac{\text{Selling Price - Purchase Price}}{\text{Purchase Price}} \times 100 \%$) can increase by $12 \%$, then the original gross profit margin for selling this product is $\qquad$ .
8. (3 points) For a certain product, if the purchase price decreases by $10 \%$, and the selling price remains unchanged, then the gross profit margin (gross profit margin = $\frac{\text { selling price - purchase price }}{\text { purchase price }} \times 100 \%$) can increase by $12 \%$, then the original gross profit margin for selling this product is $8 \%$.
【Solution】Solution: Let the original purchase price be "1", then the current purchase price is $90 \%$. According to the given conditions, we have the following equal relationship:
（selling price - $90 \% ） \div 90 \% - [（$ selling price - 1） $\div 1] = 12 \%$
Solving the equation, we get: selling price $=\frac{27}{25}$, which means the selling price is $\frac{27}{25}$ times the original purchase price.
The original gross profit margin for this product is: $\left(\frac{27}{25}-1\right) \div 1 \times 100 \% = 8 \%$
Therefore, the answer is: $8 \%$.