What is the ratio of total production for two years together for unit B to that for C?

Total production by unit B in 2001 and 2002 together = (75 + 60) = 135 Million tons
Total production by unit C in 2001 and 2002 together = (100 + 110) = 210 Million tons
∴ Required ratio = (135:210) = 9:14.