The distance between A and B is 90 kilometers. The speed of the car is twice that of the big truck. The two cars start from A to B at the same time. After arriving at B, the car returns immediately, and then the two cars meet at C. How many kilometers are there between B and C?
甲、乙两地相距90千米，小汽车的速度是大卡车的2倍，两车同时从甲地出发开往乙地，小汽车到达乙地后立即返回，然后两车在丙地相遇，乙、丙两地相距多少千米？
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">90 * (2/3)</gadget>
<output>60</output>

<gadget id="calculator">90 - 60</gadget>
<output>30</output>

<result>30</result>