The product of the mean of the numbers A and B and the number C is 270. It is known that the number of A is 30, the number of C is 6, and what is the number of B.
甲、乙两个数的平均数与丙数的积是270．已知甲数是30，丙数是6，乙数是多少．
<gadget id="calculator">270 / 6</gadget>
<output>45</output>

<gadget id="calculator">45 * 2</gadget>
<output>90</output>

<gadget id="calculator">90 - 30</gadget>
<output>60</output>

<result>60</result>