Question

the consumption of petrol for first 3 months is 88 metres and for next 9 months is 152 litres find the average consumption for the whole year

Answer 1

Total litres of petrol consumed = 88 + 152
                                                    = 240 litres
No.of months = 12
Average consumption of petrol = 240/12 
                                                     = 20 liters

Answer 2

88 + 152
                                                   
 = 240 litres
= 240/12 
                                                     
= 20 liters