Variables, Like Terms & Simplifying Expressions

How the lesson starts: Variables, Like Terms & Simplifying Expressions

Theo's mystery box
Welcome to Theo's magic show! Theo has a mystery box full of marbles. We don't know how many are inside, so we call that number x. A letter that stands for a number is a variable!
Words into math
Turn words into math. 5 more than x is x + 5. 3 less than x means start with x, then 3 roll away: x − 3. Watch out: x goes first, even though we said 3 first! 3 times x is written 3x.
Like terms
Theo pulls fruit from his hat! Apples are x and bananas are y. 3x, 4y and 2x. 3x and 2x are like terms, because they have the same letter. −2x is like them too. 4y and 7 are not.