The average of the three numbers A, B, and C is 150. The number of A is 50. The number of C is the same as that of B. What is the number of B?
甲乙丙三个数的平均数是150，甲数是50，丙数与乙数相同，乙数是多少．
<gadget id="calculator">150 * 3</gadget>
<output>450</output>

<gadget id="calculator">450 - 50</gadget>
<output>400</output>

<gadget id="calculator">400 / 2</gadget>
<output>200</output>

<result>200</result>