In a pile of sugar mixed with toffee and chocolate, if after adding 10 toffees, chocolate accounts for 60% of the total, and after adding 30 chocolates, chocolate accounts for 75% of the total, then there is milk in the original mixed sugar How much sugar?
由奶糖和巧克力混合成的一堆糖中，如果增加10颗奶糖后，巧克力占总数的60%，再增加30颗巧克力后，巧克力占总数的75%，那么，原混合糖中有奶糖多少个？
<gadget id="calculator">60 - 40</gadget>
<output>20</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>