A construction site requires 50 tons of yellow sand to be transported 5 times by a truck with a load of 4 tons, and the rest should be transported by a truck with a load of 2.5 tons. How many times should it be transported?
某工地要黄沙50吨用一辆载重4吨的汽车运5次，余下的改用载重2.5吨的汽车运，还要运几次？
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">50 - 20</gadget>
<output>30</output>

<gadget id="calculator">30 / 2.5</gadget>
<output>12</output>

<result>12</result>