The farm shipped back 106 bags of feed, each bag 35kg. After a period of use, there were still 45 bags left. How many kilograms of feed have been used?
饲养场运回106袋饲料，每袋35kg，用了一段时间后，还剩下45袋，已经用了多少千克饲料？
<gadget id="calculator">106 - 45</gadget>
<output>61</output>

<gadget id="calculator">61 * 35</gadget>
<output>2_135</output>

<result>2_135</result>