There is a flock of sheep in a livestock farm. The ratio of sheep to goats is 7:18. At the end of the year, 84 goats are sold and 84 sheep are bought. At this time, the number of goats is equal to that of sheep (62/63). How many fewer sheep are there than the original goats?
某畜牧场有一群羊，绵羊与山羊的只数比是7：18，年终卖出84只山羊，买进84只绵羊，这时山羊的只数相当于绵羊的(62/63)．这时绵羊的只数比原来的山羊少多少只
<gadget id="calculator">63 / 62</gadget>
<output>63/62 = around 1.016129</output>

<gadget id="calculator">(63/62) * 84</gadget>
<output>2_646/31 = around 85.354839</output>

<gadget id="calculator">84 + (2_646/31)</gadget>
<output>5_250/31 = around 169.354839</output>

<gadget id="calculator">(63/62) * 18</gadget>
<output>567/31 = around 18.290323</output>

<gadget id="calculator">(567/31) - 7</gadget>
<output>350/31 = around 11.290323</output>

<gadget id="calculator">(5_250/31) / (350/31)</gadget>
<output>15</output>

<gadget id="calculator">18 * 15</gadget>
<output>270</output>

<gadget id="calculator">15 * 7</gadget>
<output>105</output>

<gadget id="calculator">105 + 84</gadget>
<output>189</output>

<gadget id="calculator">270 - 189</gadget>
<output>81</output>

<result>81</result>