For Lili's birthday, divide a cake into 8 pieces on average. Lili ate 3 pieces, her father ate 2 pieces, and left the rest to her mother. What fraction of the cake did her mother eat?
丽丽过生日，把个蛋糕平均分成8块，丽丽吃了3块，爸爸吃了2块，剩下的留给妈妈，妈妈吃了这个蛋糕的几分之几？
<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">2 / 8</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (3/8) - (1/4)</gadget>
<output>3/8 = around 0.375</output>

<result>3/8 = around 0.375</result>