A new color TV consumes (3/20) kilowatt-hours of electricity per hour, which saves (2/5) electricity per hour compared with an ordinary color TV. How many kilowatt-hours does an ordinary color TV use per hour?
一台新型彩电每小时用电(3/20)千瓦时，比一台普通彩电每小时节约用电(2/5)，一台普通彩电每小时用电多少千瓦时？
<gadget id="calculator">3 / 20</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/20) / (3/5)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>