A piece of printed glass is 20 decimeters long and 15 decimeters wide. If this piece of printing is 30 yuan per square meter, how much does this piece of glass cost?
一块印花玻璃长20分米，宽15分米．如果这块印花每平方米30元，那这块玻璃需要多少元？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">30 * 20 * (3/20)</gadget>
<output>90</output>

<result>90</result>