The school cafeteria now uses 5 kilograms less coal per day than before, and now uses 20 kilograms of coal per day. How many days can it use now that it used to use coal for 40 days?
学校食堂现在每天用煤比原来节省5千克，现在每天用煤20千克，原来用40天的煤，现在可以用多少天？
<gadget id="calculator">20 + 5</gadget>
<output>25</output>

<gadget id="calculator">40 / 20</gadget>
<output>2</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>