we need to equal the denominators of the fractions to compare, as 24 is the minimum common multiple of 3 an 8, we need to convert the fractions to be divided by 24 somehow, multipliying and dividing by a correct number will do:
(2/3)(8/8) = 2*8/3*8 = 16/24
(7/8)(3/3) = 7*3/8*3 = 21/24
now we can easily compare:
21/24 > 16/24
that is:
7/8 > 2/3
Then the answer is no, 2/3 isn't greater than 7/8