The ratio of boys to girls in Class 1 of six years is 8:7, and after two more boys are transferred, the ratio of boys to girls is 9:7. How many people were there in the first class of six years?
六年一班的男生与女生的人数比是8：7，又转来2名男生后，男生与女生的人数比是9：7．六年一班原来有多少人？
<gadget id="calculator">9 / 7</gadget>
<output>9/7 = around 1.285714</output>

<gadget id="calculator">8 / 7</gadget>
<output>8/7 = around 1.142857</output>

<gadget id="calculator">(9/7) - (8/7)</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">2 / (1/7)</gadget>
<output>14</output>

<gadget id="calculator">14 / 7</gadget>
<output>2</output>

<gadget id="calculator">8 + 7</gadget>
<output>15</output>

<gadget id="calculator">2 * 15</gadget>
<output>30</output>

<result>30</result>