Larry ate 1/4 of the SNICKERS chocolate bar. Next, his sister ate 1/8 of the eaten chocolate bar. Lastly, his brother ate 2/3 of the eaten chocolate bar. How much is left of the SNICKERS bar?
So they ate 1/8 and 2/3 of that "eaten" bar of chocolate? That is... disturbing.
His brother/sister ate fractions of an "eaten chocolate bar"? When I eat something it goes into my mouth then down into my stomach and from there it does a rollercoaster ride of various processing stages then out the other end in various "ways".
To answer the math question: the answer is 3/4 of the chocolate bar still remains. The brother and sister have bigger problems. Some of which are psychological and others likely involving sepsis, infections and a whole lot of other symptoms requiring medical attention.