plus indicates that it is a sum (not a difference): 1/4 + 2/4 = 3/4. You can just add the numerators, since the denominators are the same.
Five thirds
6/3 or 2
two
the sum would be 1/4 + 3/5 = 5/20 + 12/20 = 17/20
7.000
1000
The sum of 2/9 and 1/3 is 5/9
The sum of 1/8 and 3/8 is 1/2
17/21
one seventeenth
41/60
Two over eight plus four over eight plus one over eight equals seven over eight