A car drives from city A to city B. It travels the entire distance (1/4) in the first hour, travels the remaining distance (2/5) in the second hour, and travels more in the third hour than in the first hour (3/ 10), there is still 30 kilometers away from City B. How many kilometers are there between A and B?
一辆汽车从甲城开往乙城，第一小时行了全程的(1/4)，第二小时行了剩余路程的(2/5)，第三小时比第一小时多行(3/10)，离乙城还有30千米．甲乙两成相距多少千米？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) * (2/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 + (3/10)</gadget>
<output>13/10 = around 1.3</output>

<gadget id="calculator">(1/4) * (13/10)</gadget>
<output>13/40 = around 0.325</output>

<gadget id="calculator">1 - (1/4) - (3/10) - (13/40)</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">30 / (1/8)</gadget>
<output>240</output>

<result>240</result>