Formula: If 3 numbers are in the ratio of A:B:C and have sum S, then 1st number = S×2nd number = S× 3rd number = S× The three angles of a triangle are in the ratio 5:6:7 and have sum 180°, so 1st angle = 180°× = 180° = 50° 2nd angle = 180°× = 180° = 60° 3rd angle = 180°× = 180° = 70° Edwin