There are 50 bulls in a cattle farm, and the number of cows is 9 times that of bulls. How many cows are there in the cattle farm?
养牛场养公牛50头，母牛是公牛的9倍．养牛场共养牛多少头？
<gadget id="calculator">50 * 9</gadget>
<output>450</output>

<gadget id="calculator">50 + 450</gadget>
<output>500</output>

<result>500</result>