Liam ate more
Explanation:
first convert one of the fractions to the same denominator as the other one. personally, I chose to simplify 4/10 to 2/5. this leaves us with a common denominator of 5, and it makes the problem much easier/simpler to look at.
3/5 - 2/5 = 1/5
Liam ate 1/5 more chocolate than Sam