There is a trapezoidal vegetable field with an upper base of 40m, a lower base of 60m, and a height of 30m. There are two square pools with a perimeter of 60m in the middle of the vegetable field. What is the actual planting area of this vegetable field?
有一块梯形菜地，上底为40m，下底为60m，高为30m，这块菜地中间有两个周长是60m的正方形水池．这块菜地实际种菜面积是多少？
<gadget id="calculator">40 + 60</gadget>
<output>100</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">100 * 15</gadget>
<output>1_500</output>

<gadget id="calculator">60 / 4</gadget>
<output>15</output>

<gadget id="calculator">15 * 15 * 2</gadget>
<output>450</output>

<gadget id="calculator">1_500 - 450</gadget>
<output>1_050</output>

<result>1_050</result>