The school office bought a pack of printing paper and planned to use 20 sheets per day, which can be used for 28 days. Due to paying attention to saving paper, only 16 sheets are actually used every day. How many days did it actually take?
学校办公室买进一包打印纸，计划每天用20张，可以用28天．由于注意了节约用纸，实际每天只用16张，实际用了多少天？
<gadget id="calculator">28 / 16</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">20 * (7/4)</gadget>
<output>35</output>

<result>35</result>