# 1 – Solving Basic Equations

• What is the spark at the heart of algebra?
• How does a welder know how much electrical current to apply to a new metal?
• How does a musician change a song into a new key?
• How does a diver calculate the amount of oxygen needed to go deeper than before?
• They all use equations. Equations are mathematical ways to express relationships between quantities.
• The power of equations is that they allow us to use symbols, called variables, to represent not only unknown amounts, but also those that can change or vary.
• A variable can represent the speed of a bicycle, layers on a cake, or the average number of shoppers at a mall.
• An equation can also contain more than one variable.
• Suppose you want a new cellphone contract. How do you know which carrier will give you the best deal?
• What are the variables to consider? How do they relate to one another? How could they change over time?
• Whether you want to design a dress, race a car, or paint a mural, you need to understand equations.
• In this unit, you’ll learn about the types of numbers used in basic equations, different ways to solve equations, and how to apply equations to solving real life problems.