For Honghong's birthday, her mother bought a cake and cut (1/4) for Honghong. She only ate (2/5) of it. What fraction of the whole cake did she eat?
红红过生日，妈妈买来一个蛋糕，切了(1/4)给红红，她只吃了其中的(2/5)．她吃掉的部分相当于整个蛋糕的几分之几？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/4) * (2/5)</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>