The number of A is 120, and the number of B is 20 less than 3 times of the number of A, what is the number of B?
甲数是120，乙数比甲数的3倍少20，乙数是多少．
<gadget id="calculator">120 * 3</gadget>
<output>360</output>

<gadget id="calculator">360 - 20</gadget>
<output>340</output>

<result>340</result>