Grandma bought apples and tomatoes today and spent a total of 150 yuan. It is known that apples are 3.5 yuan per kilogram and tomatoes are 2.5 yuan per kilogram. Grandma bought 35 kilograms of apples. Do you know how many kilograms of tomatoes you bought?
奶奶今天买了苹果和西红柿共花了150元，已知苹果每千克3.5元，西红柿每千克2.5元，奶奶买了35千克苹果，你知道买了几千克西红柿吗？
<gadget id="calculator">3.5 * 35</gadget>
<output>122.5</output>

<gadget id="calculator">150 - 122.5</gadget>
<output>27.5</output>

<gadget id="calculator">27.5 / 2.5</gadget>
<output>11</output>

<result>11</result>