The stationery store originally had 350 diaries. After selling (4/7) of the total number of diaries, another batch of diaries was purchased, and the current number of diaries is the original (4/5). How many diaries did you buy?
文化用品商店原来有350本日记本，卖出总本数的(4/7)后，又购进一批日记本，现在的日记本数是原来的(4/5)．又购进日记本多少本？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">350 * (4/5)</gadget>
<output>280</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">350 * (3/7)</gadget>
<output>150</output>

<gadget id="calculator">280 - 150</gadget>
<output>130</output>

<result>130</result>