If  D : S = 7 : 5 and D+S = 108, then the value of 3(D-S) : (D+S) is?

2 : 1 2 : 3 1 : 3 1 : 2

1 : 2

D : S = 7: 5 3(D-S) : (D+S) = 3(7-5) : (7+5) = (3 × 2) : 12 = 1 : 2