The greatest common divisor of the two numbers of A and B is 7, and the least common multiple is 105. It is known that the number of A is 21, and what is the number of B.
甲乙两数的最大公约数是7，最小公倍数是105，已知甲数是21，乙数是多少．
<gadget id="calculator">5 * 7</gadget>
<output>35</output>

<result>35</result>