Cabbage is 0.45 yuan per kilogram, and tomato is 1.55 yuan per kilogram. If you buy 40 kilograms each and pay 100 yuan, how much should you get back?
白菜每千克0.45元，西红柿每千克1.55元．如果各买40千克，付出100元，应找回多少元？
<gadget id="calculator">0.45 * 40</gadget>
<output>18</output>

<gadget id="calculator">1.55 * 40</gadget>
<output>62</output>

<gadget id="calculator">18 + 62</gadget>
<output>80</output>

<gadget id="calculator">100 - 80</gadget>
<output>20</output>

<result>20</result>