Надо решить ! 5/9+13/27, 3/8+5/24,5/12-13/79,3/5-1/7.

5/9 + 13/27 = 
15/27 + 13/27 =
28/27 

3/8 + 5/24 = 
9/24 + 5/24 = 
14/24 = 7/12

5/12 -13/79 = 
395/948 - 156/948 = 
239/948 

3/5 - 1/7 = 
21/35 - 5/35 = 
16/35