75% of a certain number is 220 more than 20% of it. Find this number.
某数的75%比它的20%多220，求这个数．
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/4) - (1/5)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">220 / (11/20)</gadget>
<output>400</output>

<result>400</result>