To find the price Lucy would have to pay after applying a 25% discount, you need to determine the percentage she will actually pay.
The original price represents 100% of the price. A 25% discount means that Lucy will pay 75% of the original price (because 100% - 25% = 75%).
To express 75% as a decimal for multiplication, divide by 100:
\[ 75% = \frac{75}{100} = 0.75 \]
Thus, Lucy should multiply the prices on the tags by 0.75 to find the price she would have to pay before tax.