For a test field, if the length is increased by 5 meters or the width is increased by 3 meters, the area will be increased by 45 square meters compared with the original one. What is the area of the original test field in square meters?
一块试验田，如果长增加5米，或者宽增加3米，面积都比原来增加45平方米．原来试验田的面积是多少平方米？
<gadget id="calculator">45 / 3</gadget>
<output>15</output>

<gadget id="calculator">45 / 5</gadget>
<output>9</output>

<gadget id="calculator">15 * 9</gadget>
<output>135</output>

<result>135</result>