Describe a situation where each of the following quantities might be useful.

1. -20 gallons per hour
2. -10 feet per minute
3. -0.1 kilograms per second

A submarine is only allowed to change its depth by rising toward the surface in 60-meter stages. It starts off at -340 meters.

1. At what depth is it after:

   1. 1 stage
   2. 2 stages
   3. 4 stages
2. How many stages will it take to return to the surface?

Evaluate each expression. When the answer is not a whole number, write your answer as a fraction.

1. How much higher is 500 than 400 m?
2. How much higher is 500 than -400 m?
3. What is the change in elevation from 8,500 m to 3,400 m?
4. What is the change in elevation between 8,500 m and -300 m?
5. How much higher is -200 m than 450 m?

1. A cookie recipe uses 3 cups of flour to make 15 cookies. If you had 4 cups of flour, how many cookies could you make with this recipe? (Assume you have enough of the other ingredients.)
   
2. A teacher uses 36 centimeters of tape to hang up 9 student projects. At that rate, how much tape would the teacher need to hang up 10 student projects?