There's no need for a solution as such, what you have stated is the solution. 20/3 is 6 2/3, it's also 6.66666...
7/3 is the same thing as 2 1/3.
20/3 and 7/3 are called top heavy fractions (or improper fractions) where the numerator (number on the top) is bigger than the denominator (number on the bottom).
In the case of 20/3 if you divide 20 by 3 you get 6 (6x3=18 remainder 2, the remainder 2 bit is 2 thirds).
In the case of 7/3 it's the same thing 7 will divide into 3 twice (2x3=6 with 1 remainder) the one remainder is the one third.
Hope that helps.
If you want more practice with fractions here's a cool website.
http://www.bbc.co.uk/skillswise/numbers/fractiondecimalpercentage/fractions/simplifyingfractions/factsheet.shtml