There are several oranges in a pile, give (1/3) of them to A, and the remaining (1/5) 3 less to B, and then give all the rest to C, so that the number obtained by C is 21 more than that obtained by A How many oranges are there in total?
有一堆橘子若干个，把其中的(1/3)给A，余下的(1/5)少3个给B，再把余下的全部给C，这样C得到的个数比A得到的多21个，这堆橘子共有多少？
<gadget id="calculator">21 - 3</gadget>
<output>18</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<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">(2/3) * (4/5)</gadget>
<output>8/15 = around 0.533333</output>

<gadget id="calculator">(8/15) - (1/3)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">18 / (1/5)</gadget>
<output>90</output>

<result>90</result>