For a bag of flour, 35% of the total amount is used for the first time, and 17% of the total amount is used for the second time. The second time is 3.6 kg less than the first time. How many kg of flour are there in this bag?
一袋面粉，第一次用去总数的35%，第二次用去总数的17%，第二次比第一次少用3.6千克，这袋面粉一共有多少千克？
<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">17 / 100</gadget>
<output>17/100 = around 0.17</output>

<gadget id="calculator">(7/20) - (17/100)</gadget>
<output>9/50 = around 0.18</output>

<gadget id="calculator">3.6 / (9/50)</gadget>
<output>20</output>

<result>20</result>