Answer :

LCD=35.so 30/35-14/35=16/35.welcome

6/7-2/5 -> Find LC denominator ->35

7x5=35 so multiply num and den of 6/7 by 5

5x7=35 so multiply num and den of 2/5 buy 7

Works out to: 30/35 - 14/35 

30-14= 16  answer is 16/35