Answer :

2 3/5= 10/5 + 3/15= 13/5= 2.6 
5 3/5= 25/5 + 3/5= 28/5= 5.6

or 

2 3/5+5 3/5= 7 6/5= 8 1/5

I really confuse is one or the other :P
the answer is 8_1/5 add the whole numbers 2+5 now add the fractions 3/5+3/5=6/5 and 6/5= 1_1/5 now add the whole to the 7+1=8 and now simply put the fraction in there and get 8_1/5.