Understanding Simple Equations
When we have an equation with an unknown number (we call it a variable and use letters like x, y, or n), our job is to find out what number that letter represents.
The Balance Scale Idea
Think of an equation like a balance scale. Whatever is on the left side must equal what's on the right side.
Four Types of Equations
We can use all four operations to create equations:
- Addition: x + 5 = 12
- Subtraction: x - 3 = 7
- Multiplication: x × 4 = 20
- Division: x ÷ 2 = 6
How to Solve Each Type
Addition Equations
Example: x + 5 = 12
Question: What number plus 5 equals 12?
Strategy: Think: "5 plus what makes 12?" or subtract 5 from 12.
Check: 7 + 5 = 12 ✓
Subtraction Equations
Example: x - 3 = 7
Question: What number minus 3 equals 7?
Strategy: Think: "What take away 3 leaves 7?" or add 3 to 7.
Check: 10 - 3 = 7 ✓
Multiplication Equations
Example: x × 4 = 20
Question: What number times 4 equals 20?
Strategy: Think: "4 groups of what makes 20?" or divide 20 by 4.
Check: 5 × 4 = 20 ✓
Division Equations
Example: x ÷ 2 = 6
Question: What number divided by 2 equals 6?
Strategy: Think: "What split into 2 groups makes 6 in each?" or multiply 6 by 2.
Check: 12 ÷ 2 = 6 ✓