The canteen shipped 0.9 tons of rice, and the flour shipped in was 0.5 tons less than three times the weight of rice. How many tons of flour did the canteen ship?
食堂运来大米0.9吨，运来的面粉比大米重量的3倍少0.5吨．食堂运来面粉多少吨？
<gadget id="calculator">0.9 * 3</gadget>
<output>2.7</output>

<gadget id="calculator">2.7 - 0.5</gadget>
<output>2.2</output>

<result>2.2</result>