Average expenditure for the first 5 months = Rs. 1200 ⇒ Total expenditure in first 5 months = 5×1200=Rs.6000 Similarly, total expenditure in next 7 months = 7×1300=Rs.9100 Total savings = Rs. 2900 Thus, total annual income = 6000+9100+2900=Rs.18000 ∴ Monthly average income =