The greatest common divisor of A and B is 14, the least common multiple is 84, and the number of B is 42. What is the number of A?
甲、乙的最大公约数是14，最小公倍数是84，乙数是42，甲数是多少．
<gadget id="calculator">14 * 2</gadget>
<output>28</output>

<result>28</result>