word problem: Dropping less than two inches per mile after emerging from the mountains, algebra homework help

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, 1.6 trillion gallons, could supply all of country A’s households for four months.

Based on this statement, determine how much water an average household uses each month. Assume that there are 100

million households in country A.

Country A uses approximately gallons per household per month.

(Type a whole number.)