A has 500 yuan, and A gives 20% to B. The two people have exactly the same amount of money. How much money does B have?
甲有500元钱，甲给乙20%，两人钱数正好相等，乙原有多少钱？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">500 * (1/5)</gadget>
<output>100</output>

<gadget id="calculator">500 - 100 - 100</gadget>
<output>300</output>

<result>300</result>