A triangle with a base of 5 cm and a height of 4 cm is enlarged by 3:1. What is the area of the triangle in square centimeters?
一个三角形底5厘米、高4厘米，把它按3：1放大，三角形面积是多少平方厘米？
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">15 * 12</gadget>
<output>180</output>

<gadget id="calculator">180 / 2</gadget>
<output>90</output>

<result>90</result>