It is known that the area of triangle ABC is 9, and the ratio of it to a group of sides of another triangle DEF is 1:5, and the heights of the sides of this group are equal, what is the area of triangle DEF?
已知三角形ABC的面积是9，且它与另一三角形DEF的一组边之比为1：5，这组边上的高相等，则三角形DEF的面积是多少？
<gadget id="calculator">9 * 5</gadget>
<output>45</output>

<result>45</result>