[(1/3)^2 + (4/5)^2 - (7/15)^2] : [(37/30)^2 - (7/6)^2 ] : 3,(3) =
= (1/9 + 16/25 - 49/225) : (1369/900 - 49//36) : (33 - 3)/9 =
= (25/225+144/225-49/225) : ( 1369/900 - 49×25/900) : 30/9 =
= 120/225 : (1369/900-1225/900): 10/3 =
= 120/225 : 144/900 : 10/3 =
= 120/225 × 900/144 × 3/10 =
= 120×4/144 × 3/10 =
= 480/144 × 3/10 =
= 480/48×10 =
= 480/480 =
= 1