Bottle A contains 500 grams of fruit juice, bottle B contains 900 grams of fruit juice, how many grams should be poured from bottle B to bottle A, the weight of the two bottles of fruit juice is the same.
甲瓶有果汁500克，乙瓶有果汁900克，应从乙瓶向甲瓶倒多少克，两瓶果汁就一样重．
<gadget id="calculator">900 + 500</gadget>
<output>1_400</output>

<gadget id="calculator">1_400 / 2</gadget>
<output>700</output>

<gadget id="calculator">900 - 700</gadget>
<output>200</output>

<result>200</result>