On a straight road, at a certain moment, there is a passenger car in front and a car behind, and a truck is driving in the same direction between the bus and the car. After 10 minutes, the car catches up with the truck. , After another 5 minutes, the car catches up with the passenger car, and after that, after another t minutes, the truck catches up with the passenger car, then t=how much.
在一条笔直的公路上，某一时刻，有一辆客车在前，一辆小轿车在后，一辆货车在客车与小轿车的正中间同向行驶，过了10分钟，小轿车追上了货车，又过了5分钟，小轿车追上了客车，此后，再过t分钟，货车追上了客车，则t=多少．
<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">10 / 1</gadget>
<output>10</output>

<gadget id="calculator">10 + 5</gadget>
<output>15</output>

<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(2/15) - (1/10)</gadget>
<output>1/30 = around 0.033333</output>

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

<gadget id="calculator">30 - 15</gadget>
<output>15</output>

<result>15</result>