A bank charges a service fee of \$7.50 per month for a checking account.

A bank account has \$85.00. If no money is deposited or withdrawn except the service charge, how many months until the account balance is negative?

The table shows transactions in a checking account.

1. Find the total of the transactions for each month.
2. Find the mean total for the four months.

A large aquarium of water is being filled with a hose. Due to a problem, the sensor does not start working until some time into the filling process. The sensor starts its recording at the time 0 minutes. The sensor initially detects the tank has 225 liters of water in it.

1. The hose fills the aquarium at a constant rate of 15 liters per minute. What will the sensor read at the time 5 minutes?

2. Later, someone wants to use the data to find the amount of water at times before the sensor started. What should the sensor have read at the time -7 minutes?

A furniture store pays a wholesale price for a mattress. Then, the store marks up the retail price to 150% of the wholesale price. Later, they put the mattress on sale for 50% off of the retail price. A customer just bought the mattress on sale and paid \$1,200.

1. What was the retail price of the mattress before the discount?
2. What was the wholesale price, before the markup?

1. A restaurant bill is $21. You leave a 15% tip. How much do you pay including the tip?

2. Which of the following represents the amount a customer pays including the tip of 15% if the bill was \(b\) dollars? Select all that apply.