A batch of coal is transported 3.5 tons each time, and the shipment is finished in 9 times. If an extra ton is shipped each time, how many times can it be shipped?
一批煤，每次运3.5吨，9次运完，如果每次多运1吨，几次可以运完？
<gadget id="calculator">3.5 + 1</gadget>
<output>4.5</output>

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

<gadget id="calculator">3.5 * 2</gadget>
<output>7</output>

<result>7</result>