A fruit merchant bought 100 apples from a fruit wholesaler and spent a total of 120 yuan. At retail, 70 of the larger apples were sold at 1.8 yuan each, and the remaining 30 smaller apples were sold at 0.5 yuan each. sell. Find the profit rate of the fruit merchant in this transaction.
一水果商从水果批发行购进苹果100个，共花了120元，在零售时，其中70个较大的苹果以每个1.8元卖出，余下30个较小的苹果以每个0.5元卖出．求这个水果商在这笔买卖中的盈利率．
<gadget id="calculator">1.8 * 70</gadget>
<output>126</output>

<gadget id="calculator">0.5 * 30</gadget>
<output>15</output>

<gadget id="calculator">126 + 15</gadget>
<output>141</output>

<gadget id="calculator">141 - 120</gadget>
<output>21</output>

<gadget id="calculator">21 / 120</gadget>
<output>7/40 = around 0.175</output>

<result>7/40 = around 0.175</result>