The number of female workers in a factory is 2/5 that of male workers. Now 5 female workers are transferred in. At this time, the ratio of the number of female workers to the total number of workers is 3:10. How many female workers were there in this factory?
一个工厂女工人数是男工的(2/5)，现在调入了5名女工，这时女工人数与总人数的比为3：10，这个工厂原有女工多少人？
<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/7) - (2/5)</gadget>
<output>1/35 = around 0.028571</output>

<gadget id="calculator">5 / (1/35)</gadget>
<output>175</output>

<gadget id="calculator">175 * (2/5)</gadget>
<output>70</output>

<result>70</result>