There are 90 tons of cargo at the station, which can be transported 12 times by two vehicles. It takes 20 times to be transported by car A alone, how many times can it be transported by car B alone?
车站有90吨货物，两辆汽车合运12次可以运完．由甲车单独运要20次可以运完，由乙车单独运几次可以运完？
<gadget id="calculator">90 / 12</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">90 / 20</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">(15/2) - (9/2)</gadget>
<output>3</output>

<gadget id="calculator">90 / 3</gadget>
<output>30</output>

<result>30</result>