The long-distance bus from A to B used to take 7 hours, but after opening the expressway, the distance is nearly 60 kilometers, and the average speed increases by 30 kilometers per hour, and it only takes 4 hours to get there. Find the distance between the highways of A and B?
从甲地到乙地的长途汽车原来需行驶7小时，开通高速公路后，路程近了60千米，而车速平均每小时增加了30千米，只需4小时即可到达．求甲、乙两地的高速公路的距离？
<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<gadget id="calculator">120 + 60</gadget>
<output>180</output>

<gadget id="calculator">7 - 4</gadget>
<output>3</output>

<gadget id="calculator">180 / 3</gadget>
<output>60</output>

<gadget id="calculator">7 * 60</gadget>
<output>420</output>

<result>420</result>