The product of the half of the sum of the numbers A and B and the number C is 270. It is known that the number A is 30 and the number C is 6. What is the number B?
甲、乙两数和的一半与丙数的积是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>