There are 50 black rabbits on the grass, and the number of white rabbits is three times that of black rabbits. How many rabbits are there in the grass?
草地上有黑兔50只，白兔的只数是黑兔的3倍，草地上共有兔多少只？
<gadget id="calculator">50 * 3</gadget>
<output>150</output>

<gadget id="calculator">150 + 50</gadget>
<output>200</output>

<result>200</result>