Before revision: And there are 81 + 23 + 27 + 89 = 220 progeny showing recombination between genes B and C. Thus the expected rate of double recombination is (350 / 1000) * (220 / 980 ) = 0.0786, or 78.6 per 1000.
After revision: And there are 81 + 23 + 27 + 89 = 220 progeny showing recombination between genes B and C. Thus the expected rate of double recombination is (350 / 1000) * (220 / 1000 ) = 0.077, or 77 per 1000.