Iam not quite sure how to do these.

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, 5.6 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 100 million households in country a. country a uses approximately nothing gallons per household per month.

Write two subtraction equations that are equivalent to 5 + 12 = 17.

X-10/4 when x = –18 a 7 b –2 c –7 d 2