Question 996695
Take the process one step at a time.


Eat {{{2/3}}} of 1;  {{{1/3}}} is still.


Eat {{{2/5}}} of {{{1/3}}}; there still is  {{{3/5}}} of {{{1/3}}} not yet eaten.  This not-yet-eaten part is what remains of the original 1 bar.


Final calculation:  {{{highlight((3/5)(1/3)=highlight(1/5))}}}