7th grade math help me please

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.

You are a clerk at convenience store. a customer owes 11.69 for a bag of potatoes chips. she gives you a five dollar bill. how much change should the customer receive?

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?