There are two sets of numbers, the mean of the first set is 18, the mean of the second set is 15, the total mean of these two sets is 17. How many times is the number of the first group of numbers the number of the second group of numbers?
有两组数，第一组数的平均数是18，第二组数的平均数是15，这两组数的总平均数是17．那第一组数的个数是第二组数的个数的几倍？
<gadget id="calculator">17 - 15</gadget>
<output>2</output>

<gadget id="calculator">18 - 15</gadget>
<output>3</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 3 / (1/3)</gadget>
<output>2</output>

<result>2</result>