Mr. Wang rode a bicycle from school to the county to do business. It is known that he has traveled the entire distance (2/7). If he travels another 15km, the ratio of the distance traveled to the remaining distance is 5:2. How many kilometers is the distance from the school to the county? ?
王老师从学校骑车去县城办事，已知走了全程的(2/7)，如果再行15km，已行路程和剩下路程的比是5：2，学校到县城的路程是多少千米？
<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(5/7) - (2/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">15 / (3/7)</gadget>
<output>35</output>

<result>35</result>