The students collected tree species, the first group collected (3/5) kilograms, the second group collected (3/4) kilograms, and the number of kilograms collected by the third group was less than the total number collected by the first and second groups (3/10) kilograms , How many kilograms did the third group collect?
同学们采集树种，第一组采集(3/5)千克，第二组采集(3/4)千克，第三组采集的千克数比第一、二组采集的总数少(3/10)千克，第三组采集多少千克？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/4) - (3/10)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(3/5) + (9/20)</gadget>
<output>21/20 = around 1.05</output>

<result>21/20 = around 1.05</result>