Question

a petrol consumption for first three month is 88 liter and next 9 month is 152 liter
what is the average consupution for the whole year
how to solve

Answer 1

for 3 months =88liters 
for 9 months =152liters
that means he used 240 liters for one year
therefore average consumption is 240 liters

Answer 2

88 litres for 3 months.
152 litres for 9 months.
Total consumption of 12 months=88 litres+152 litres that is 240 litres.
therefore average consumption will be 240 litres divided by 3+9 months and therefore your answer will be 20 litres.