It is known that 60% of a number is 90, what is its 40%.
已知一个数的60%是90，它的40%是多少．
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">90 / (3/5)</gadget>
<output>150</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">150 * (2/5)</gadget>
<output>60</output>

<result>60</result>