The Snack Stand Setup
Story
A student council packs snack bags for a game. Each bag has 3 granola bars, and there are always 2 extra bars on the table.
The number of bags can change. Instead of writing a new sentence each time, algebra lets us use a letter.
x means the number of snack bags. The expression 3x + 2 tells how many bars there are in all.
Build the Expression
Interactive
Variable
x = 4
Expression
3x + 2 = 14
Equation
3x + 2 = 14
What the expression shows
Extra bars
1
1
Total bars
14
Expression or Equation?
Math
1
Variable
x is a placeholder for a number that can change or may be unknown.
2
Expression
3x + 2 has numbers, a variable, and operations. It does not have an equal sign.
3
Equation
3x + 2 = 14 says two quantities are equal. It can be true or false.
Try x = 4. The left side becomes 3(4) + 2 = 14, so the equation is true.
Why it matters
Equations are useful because they let us describe a situation before we know every number. Once the equation is written, testing a solution means replacing the variable and asking: do both sides match?