A piece of triangular glass, the base length is 20.8 decimeters, and the height is 4 decimeters less than half of the base. The price of glass per square decimeter is 68 yuan. How much does it cost to buy this piece of glass?
一块三角形的玻璃，底边长20.8分米，高是底的一半少4分米．每平方分米玻璃的价钱是68元，买这块玻璃要用多少钱？
<gadget id="calculator">20.8 / 2</gadget>
<output>10.4</output>

<gadget id="calculator">10.4 - 4</gadget>
<output>6.4</output>

<gadget id="calculator">6.4 / 2</gadget>
<output>3.2</output>

<gadget id="calculator">20.8 * 3.2</gadget>
<output>66.56</output>

<gadget id="calculator">66.56 * 68</gadget>
<output>4_526.08</output>

<result>4_526.08</result>