The difference between A and B is 30, and (3/10) of A's number is equal to (1/3) of B's number. What is A's number?
甲、乙两数相差30，其中甲数的(3/10)与乙数的(1/3)相等，甲数是多少．
<gadget id="calculator">30 * 10</gadget>
<output>300</output>

<result>300</result>