Hi there! Today we're going to learn about algebra, which is like solving fun puzzles with mystery numbers! You probably already know how to solve problems like 5 plus what equals 8. In algebra, instead of using a question mark, we use letters like x to represent the mystery number we're trying to find.
Now let's learn about the most important rule in algebra: the balance scale rule! The equals sign is like a balance scale. Whatever is on the left side must equal whatever is on the right side. Here we have x plus 3 equals 7. Think of it as a mystery box plus 3 blocks on one side, and 7 blocks on the other side. The scale is balanced because both sides have the same total value.
Now let's solve our first equation step by step! We have x plus 3 equals 7. To find x, we need to get it by itself. Since we have plus 3 on the left side, we subtract 3 from both sides to keep the balance. When we subtract 3 from the left side, the plus 3 disappears, leaving just x. When we subtract 3 from 7 on the right side, we get 4. So x equals 4!
Let's solve a real-world problem! Sarah had some cookies, but we don't know how many. Her friend gave her 5 more cookies. Now Sarah has 12 cookies in total. How many cookies did Sarah start with? We can write this as an equation: c plus 5 equals 12, where c represents the cookies Sarah started with. To solve this, we subtract 5 from both sides: c equals 12 minus 5, which equals 7. So Sarah started with 7 cookies!
Congratulations! You're now an algebra detective! You've learned that variables are mystery numbers represented by letters, the equals sign means both sides must balance, and you solve equations by doing the same operation to both sides. Algebra helps us solve real-world problems like figuring out how many cookies Sarah had. Keep practicing with different equations, and remember - every time you solve an equation, you're being a math detective finding the mystery number!