The red scarf is a triangle. It is known that its base is 40cm and its height is 15cm. How many cm2 of red cloth are needed to make a red scarf like this.
红领巾是三角形，已知它的底是40cm，高是15cm，做一面这样的红领巾需要多少c㎡的红布．
<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">40 * (15/2)</gadget>
<output>300</output>

<result>300</result>