Dropping less than two inches per mile after emerging from the mountains, a river drains into the ocean. one day's discharge at its mouth, 5.65.6 trillion gallons, could supply all of country a's households for seven months.
based on this statement, determine how much water an average household uses each month. assume that there are 1100 million households in country a.
country a uses gallons per household per month. (type a whole number.)

Let me know if this is wrong, but I would do approach it like this.  So we know that 5.656 trillion gallons could supply all of the households for 7 months, and the question asks how much water each household uses per month.  So to get it down to a monthly usage, we need to find out how many gallons that is per month.  Lets divide 5.656 trillion by 7, that will give us the monthly usage.  Now, the country has 1.1 million households. So lets divide the first answer by 1.1 million.  (Not really sure on your numbers, 1100 million would actually be 1.1 trillion).  Basically though you just need to get the first number down to the a amount per month, then divide by the households to get the average usage per house.