The number A is 90, 20% of the number A is equal to 30% of the number B, what is the number B?
甲数是90，甲数的20%等于乙数的30%，乙数是多少．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(1/5) / (3/10)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">90 * (2/3)</gadget>
<output>60</output>

<result>60</result>