The iron and steel factory wants to produce a batch of steel, and plans to produce 800 tons per day, which will be completed in 20 days. The actual daily production is 25% more than the original plan, how many days earlier than the original plan? (answer in two ways)
钢铁厂要生产一批钢材，计划每天生产800吨，20天完成．实际每天比原计划多生产生产25%，实际比原计划提前几天完成？(用两种方法解答)
<gadget id="calculator">800 * 20</gadget>
<output>16_000</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">800 * (1/4) * 20</gadget>
<output>4_000</output>

<gadget id="calculator">4_000 - 16_000</gadget>
<output>-12_000</output>

<gadget id="calculator">16_000 + (-12_000)</gadget>
<output>4_000</output>

<gadget id="calculator">800 * (1/4)</gadget>
<output>200</output>

<gadget id="calculator">800 + 200</gadget>
<output>1_000</output>

<gadget id="calculator">4_000 / 1_000</gadget>
<output>4</output>

<result>4</result>