50% of the number A is 45, what is the number A?
甲数的50%是45，甲数是多少．
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">45 / (1/2)</gadget>
<output>90</output>

<result>90</result>