There is a pile of bricks. After moving away (1/4), 306 bricks are brought in. At this time, the pile of bricks is more than the original one (1/5). Ask how many bricks there are in the pile.
有一堆砖，搬走(1/4)后又运来306块，这时这堆砖比原来还多了(1/5)，问原来这堆砖有多少块．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) - 1</gadget>
<output>-4/5 = around -0.8</output>

<gadget id="calculator">(1/4) + 1 + (-4/5)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">306 / (9/20)</gadget>
<output>680</output>

<result>680</result>