There are some fruits, (1/5) of these fruits are sold on the first day, and the rest (4/9) are sold on the second day, how many of these fruits are sold in two days.
有一些水果，第一天售出这些水果的(1/5)，第二天售出余下的(4/9)，两天共售出这些水果的多少．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(4/5) * (4/9)</gadget>
<output>16/45 = around 0.355556</output>

<gadget id="calculator">(1/5) + (16/45)</gadget>
<output>5/9 = around 0.555556</output>

<result>5/9 = around 0.555556</result>