Directions: Write a equation for the function described. Then find the input.

The output of a function is 13 more than 4 times the input. Find the input when the

output is 17.

The output of a function is 7 more than 1/2 of the input. Find the input when the output is 19.

The output of a function is 16 less than 5 times the input. Find the input when the output is 8.5.

One model of a portable keyboard, Model A, has a total of 61 black and white keys. It has five full octaves with 5 black keys in each octave. The Model B portable keyboard has 76 black and white keys. It has six full octaves with 5 black keys in each octave and one extra black key.

a. Find the number of white keys on the Model A keyboard.

b. Find the number of white keys on the Model B keyboard.

c. How many more white keys are there on the Model B keyboard than there are on the Model A keyboard?

A town's water tower holds 1 million gallons of water. During the day,

the tower is only 2/5 of its full capacity. The tower will be refilled at night, when water consumption is low, using a pump that pumps water into the tower at a rate of 2000 gallons of water per minute. How long will it take to bring the tower back to full capacity? Explain how you got your answer. If the town had a pump that only filled the tank at 500 gallons per minute, how much longer would it take to fill the tank?