An expression is a mathematical phrase that can contain numbers, variables, and operations. It represents a value and can be evaluated to obtain a numerical result.

There are several types of expressions:

**Numerical Expression:**A mathematical expression that contains only numbers and operations. For example, 5 + 3 * 2.**Variable Expression:**An expression that contains variables, numbers, and operations. For example, 3x + 7.**Algebraic Expression:**A combination of variables, numbers, and operations. For example, 2x + 5y - 3.**Complex Expression:**An expression that contains multiple terms and operations. For example, (3x + 2) * (4y - 1).

Common operations used in expressions include:

**Addition (+)****Subtraction (-)****Multiplication (*)****Division (/)****Exponents (^)**

To evaluate an expression, you perform the operations according to the rules of arithmetic. For example, to evaluate the expression 3x + 7 when x = 2, you substitute the value of x and perform the operations: 3(2) + 7 = 6 + 7 = 13.

Here are some examples of expressions:

- 2x + 5y - 3
- (3a + 2b) * (4c - 1)
- 5 + 3 * (8 - 2)

These examples illustrate the different types of expressions and the operations involved in evaluating them.

.Study GuideNumbers and percents Worksheet/Answer key

Numbers and percents Worksheet/Answer key

Numbers and percents Worksheet/Answer key

Numbers and percents

Number and Operations (NCTM)

Understand numbers, ways of representing numbers, relationships among numbers, and number systems.

Work flexibly with fractions, decimals, and percents to solve problems.

Understand and use ratios and proportions to represent quantitative relationships.

Compute fluently and make reasonable estimates.

Develop, analyze, and explain methods for solving problems involving proportions, such as scaling and finding equivalent ratios.