Grandpa Wang raised a total of 200 white rabbits and black rabbits, among which the number of black rabbits is 1/3 of that of white rabbits. How many black rabbits are there?
王爷爷养了白兔和黑兔共200只，其中黑兔的只数是白兔的(1/3)，黑兔有多少只？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 + (1/3)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">200 / (4/3)</gadget>
<output>150</output>

<gadget id="calculator">(1/3) * 150</gadget>
<output>50</output>

<result>50</result>