so, on Monday he ate 1/7, that means from a whole 7/7, take away 1/7, the leftover was 6/7 then.
on Tuesday, he ate 1/6 of the leftover, namely, 1/6 of 6/7.
now, how much is 1/6 of 6/7? well, is just their product, [tex]\bf \cfrac{1}{6}\cdot \cfrac{6}{7}\implies \cfrac{1}{7}[/tex]
now, so he really ate 1/7 of the whole thing on Tuesday, there were 6/7 remaining, how much is 6/7 - 1/7? yeap, you guessed it, 5/7.
