1) (5a - b) / 3c + (a - 2b) / 3c= (5a + a - b - 2b) / 3c= (6a - 3b) / 3c= 3(2a - b) / 3c= (2a - b) / c
2) (2n - 3) / (5n^2) - (7n - 3) / (5n^2)= (2n - 7n - 3 + 3) / (5n^2)= (-5n) / (5n^2)= -1/n
1) (5a - b) / 3c + (a - 2b) / 3c
= (5a + a - b - 2b) / 3c
= (6a - 3b) / 3c
= 3(2a - b) / 3c
= (2a - b) / c
2) (2n - 3) / (5n^2) - (7n - 3) / (5n^2)
= (2n - 7n - 3 + 3) / (5n^2)
= (-5n) / (5n^2)
= -1/n