There are 350 copies of "Mathematical Thinking Training" in the bookstore, 40% of them are sold on the first day, and 3/7 of the total are sold on the second day, how many copies are left?
书店里有《数学思维训练》350本，第一天卖出40%，第二天卖出总数的(3/7)，还剩下多少本？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (2/5) - (3/7)</gadget>
<output>6/35 = around 0.171429</output>

<gadget id="calculator">350 * (6/35)</gadget>
<output>60</output>

<result>60</result>