The ratio of the numbers A and B is 4:7, the number B is 12 more than the number A, then what is the number A?
甲乙两数的比为4：7，乙数比甲数多12，那么甲数是多少．
<gadget id="calculator">7 / 4</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">(7/4) - 1</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">12 / (3/4)</gadget>
<output>16</output>

<result>16</result>