Teacher Li spent 24 yuan and 40 cents on math reference books, and 28 yuan and 50 cents on Chinese reference books. She paid the salesperson 60 yuan. How much should she get back? (calculated with decimals)
李老师买数学参考书用了24元4角，买语文参考书用了28元5角，她付给售货员60元，应找回多少元钱？(用小数计算)
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">24 + (2/5)</gadget>
<output>122/5 = around 24.4</output>

<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">28 + (1/2)</gadget>
<output>57/2 = around 28.5</output>

<gadget id="calculator">(122/5) + (57/2)</gadget>
<output>529/10 = around 52.9</output>

<gadget id="calculator">60 - (529/10)</gadget>
<output>71/10 = around 7.1</output>

<result>71/10 = around 7.1</result>