A and B each have a certain amount of yuan. After A gives (1/5) to B, B gives (1/4) to A. At this time, they each have 90 yuan. How much did B originally have?
甲乙各有若干元，甲拿出(1/5)给乙后，乙拿出(1/4)给甲，这时他们各有90元．乙原来有多少元．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">90 * 2 * (1/5) * (1/4)</gadget>
<output>9</output>

<gadget id="calculator">90 * 2 * (1/5)</gadget>
<output>36</output>

<gadget id="calculator">90 - 36</gadget>
<output>54</output>

<gadget id="calculator">9 + 54</gadget>
<output>63</output>

<gadget id="calculator">(1/5) * (1/4)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) - (1/4) - (1/5)</gadget>
<output>-2/5 = around -0.4</output>

<gadget id="calculator">1 + (-2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">63 / (3/5)</gadget>
<output>105</output>

<result>105</result>