➗ Algebra

Numbers Turn Into Puzzles

Algebra is math with letters and symbols.

We use a letter, like x, to stand for a missing number.

Examples:

• 3 + x = 10
• 5 · y = 20

You use algebra when you think:

> "What number do I need so this works?"

Algebra helps us solve everyday problems, like sharing pizza or planning money.

Algebra Words You Need

• Variable: a letter for a missing number (x, y)
• Expression: numbers and letters with +, −, ×, ÷ (like 3x + 2)
• Equation: two sides with an = sign (like 3x = 12)

Think:

• Expression = one side
• Equation = a full balance with = in the middle ⚖️

Why Use Letters?

Letters make rules work for many problems.

Example rule:

• If 2x = 10, then x = 5

This idea works for:

• 2·? = 10
• 2 apples per bag, 10 apples total → 5 bags

So one algebra rule can solve lots of real problems.

Real-Life Example 🍕

You and a friend share a pizza with 8 slices.

You eat 3 slices.

How many does your friend get?

Let x be your friend’s slices.

• 3 + x = 8

To find x, we solve this equation.

Algebra turns this story into math we can work with.