What is the area of a triangle that is 30 square centimeters less than the area of its parallelogram with the same base and height?
一个三角形比与它等底等高的平行四边的面积少30平方厘米，则这个三角形的面积是多少．
<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">30 / 1</gadget>
<output>30</output>

<result>30</result>