A's age is 4 times less than B's age by 3, A's age in 3 years is equal to B's age in 9 years, how old is A now?
甲的年龄比乙的年龄的4倍少3，甲在3年后的年龄等于乙9年后的年龄，问甲现在多少岁．
<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<gadget id="calculator">6 + 3</gadget>
<output>9</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">9 / 3</gadget>
<output>3</output>

<gadget id="calculator">3 + 6</gadget>
<output>9</output>

<result>9</result>