The unit price of the clock is 28 yuan, and the unit price of the desk lamp is 45 yuan. Xiaohua paid 100 yuan to buy a clock and a desk lamp, how much should I get back?
钟的单价是28元，台灯的单价是45元．小华付出100元，买了一个钟和一盏台灯，应找回多少元？
<gadget id="calculator">100 - 28 - 45</gadget>
<output>27</output>

<result>27</result>