Identify the following as either an expression or equation.
$4(a-2)=21$

• A. Expression
• B. Equation

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the difference between an expression and an equation. An expression is a combination of numbers, variables, and operations without an equals sign, while an equation includes an equals sign showing that two expressions are equal.
2. Step 2: Look at the given mathematical statement: \$4\left(a-2\right)=21$.
3. Step 3: Notice that this statement contains an equals sign (\(=\)), which means it is setting two quantities equal to each other.
4. Step 4: Since there is an equals sign, this statement is not just an expression; it is an equation.
5. Step 5: Therefore, identify \$4\left(a-2\right)=21$ as an equation.