The number of A is 16.5, which is 3.5 less than twice the number of B. What is the number of B?
甲数是16.5，比乙数的2倍少3.5，乙数是多少？
<gadget id="calculator">16.5 + 3.5</gadget>
<output>20</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>