A grain stockpiles 45 tons of grain. After the first shipment of 29.5 tons, another batch of grain was shipped in. After the second shipment of 18.6 tons, there were still 22.4 tons left. How many tons are there in a batch of grain?
一个粮库存粮食45吨，第一次运出29.5吨后又运进一批粮食，第二次运出18.6吨后还剩下22.4吨．求运进的一批粮食有多少吨？
<gadget id="calculator">22.4 - 45</gadget>
<output>-22.6</output>

<gadget id="calculator">29.5 + 18.6 + (-22.6)</gadget>
<output>25.5</output>

<result>25.5</result>