25% of a number is 30 less than its 75%, find the number.
一个数的25%比它的75%少30，求这个数．
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) - (1/4)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">30 / (1/2)</gadget>
<output>60</output>

<result>60</result>