- Topics At a Glance
- Variables
- Variables as Unknown Quantities
- Variable Notations
- Constants
- Expressions and Equations
- Rearranging Expressions
- Commutative Properties
- Associative Properties
- Distributive Properties
- Factoring (Distributive Property in Reverse)
- Combining Like Terms
- Eliminating Parentheses
- Simplifying
- Equations, Functions, and Formulas
- Equations
- Functions
- Independent and Dependent Variables
- Formulas
- Applications to Toolbox
- Evaluating Expressions by Substitution
- Evaluating Formulas by Substitution
- Geometric Formulas
- Four-Sided Shapes
- Three-Sided Shapes
- Circles
**Unit Conversion****Temperatures**- Weights
- Distances and Speeds
- Money
- In the Real World
- I Like Abstract Stuff; Why Should I Care?
- How to Solve a Math Problem

Let *F* be degrees Fahrenheit, a unit commonly used in the United States, and let *C* be degrees Celsius, used almost everywhere else. Oh, but ours is the right one. *Sure*...

We can convert from one temperature system to the other using the following formulas:

If the temperature is 92 degrees Fahrenheit, what is the temperature in Celsius?

First of all, it shouldn't matter. We are at home, indoors, mostly naked and standing in the kitchen with the refrigerator door wide open.

Okay, we will play along.

Let *F* = 92. Then *,* and the temperature is 30 degrees Celsius.

That sounds deceptively cool. No wonder everywhere else is crazy.

Exercise 1

Alex is visiting his friend in Pamplona and wants to adjust the thermostat to 68 degrees F. However, the thermostat only gives readings in Celsius. To what temperature should Alex set the thermostat? Does it really matter? How well will the air conditioning work once a bull tears a hole through the drywall on its way through town?

Exercise 2

Marcie is making cookies using a recipe from England...because England is known for its high quality food? The recipe says to bake the cookies at 190 degrees Celsius. Marcie, who usually bakes her cookies at 190 degrees Fahrenheitâ€”hence the general mushinessâ€”has an oven with a temperature gauge showing degrees Fahrenheit, and has markings every 25 degrees (at 25, 50, 75, etc.). To what temperature should Marcie set her oven if she doesn't want to turn out her usual subpar product?