For a bag of candy, the teacher first gave all (1/3) to Mingming, then gave the remaining (1/5) less 3 pieces to Honghong, and finally gave the rest of the candy to Fangfang. In this way, Fangfang got 21 more pieces of sugar than Mingming. How many pieces did the bag of sugar have in total?
一袋糖，老师先把全部的(1/3)分给了明明，再把余下的(1/5)少3块分给了红红，最后把剩下的糖都分给了芳芳．这样芳芳分到的糖比明明多21块，原来这袋糖一共有多少块．
<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 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/3) * (1/5)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) - (1/3) - (1/5) - (1/3)</gadget>
<output>-4/5 = around -0.8</output>

<gadget id="calculator">1 + (-4/5)</gadget>
<output>1/5 = around 0.2</output>

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

<result>90</result>