A pack of A4 copy paper, 25 sheets per day, will be used up in 20 days. How many days can it be used if you use less than 5 sheets per day?
一包A4复印纸，每天用25张，20天正好用完．如果每天少用5张，那么可以用多少天？
<gadget id="calculator">25 - 5</gadget>
<output>20</output>

<gadget id="calculator">20 / 20</gadget>
<output>1</output>

<gadget id="calculator">25 * 1</gadget>
<output>25</output>

<result>25</result>