Mother bought a piece of cake weighing (9/10) kilograms, mother ate (2/10) kilograms, father ate (2/10) kilograms more than mother, the rest was eaten by the baby, the baby ate How many kilograms of cake?
妈妈买了一张重(9/10)千克的饼，妈妈吃了(2/10)千克，爸爸比妈妈多吃(2/10)千克，剩下的被宝宝都吃光了，宝宝吃了多少千克的饼？
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) + (1/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(9/10) - (1/5) - (2/5)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>