In a Km race A can beat B by 80 m and B can beat C by 60 m. In the same race, A can beat C by :

While A runs 1000 m, B runs 1000 - 80 = 920 m and
While B runs 1000 m, C runs 1000 - 60 =940 m.
∴ While B runs 920 m; C runs
940 / 1000 × 920 = 4324 / 5 m
∴ While B runs 920 m; C runs 940 × 920 / 1000 = 4324 / 5 m
∴ While A runs 1000 m, C runs 4324 / 5 m
∴ A can beat C by 1000 - 4324 / 5 = 676 / 5 = 135¹⁄₅ m.