i have 3 kg 4 kg and 5 kg on one side and 5 kg and 7 kg on the other side which two tiles do i swap to have the same amount on both sides

Answer 1

3 + 4 + 5 on the left for a total of ?
5 + 7 on the right for a total of ?

Are they equal? If they are not, then you'll need to swap.