The number A is 25, which is 5 less than twice the number B. What is the number B?
甲数是25，比乙数的2倍少5，乙数是多少．
<gadget id="calculator">25 + 5</gadget>
<output>30</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<result>15</result>