Evaluating Expressions with one Variable  Learn  Contents and Search  Practice  Next Lesson  Play  Previous Lesson  Explore   Feedback   Evaluating an Expression with One Variable A mathematical expression can have a variable as part of the expression. If x=3, the expression 7x + 4 becomes 7 * 3 + 4 which is equal to 21 + 4 or 25. To evaluate an expression with a variable, simply substitute the value of the variable into the expression and simplify. Return to Top Practice Evaluate the Expression =   You have correct and   incorrect.  This is percent correct. Return to Top Tell Others About This Site Play Game What is it? Best Score How many correct answers can you get in 60 seconds? Extra time is awarded for each correct answer. Play longer by getting more correct. How fast can you get 20 more correct answers than wrong answers? Sudoku Return to Top Explore Math Lessons by Grade Kindergarten  First Second Third Fourth Fifth Sixth Seventh Eighth Review Math Topics Addition Algebra Comparing Counting Decimals Division Equations Estimation Exponents Fractions Geometry Graphs Measurement Mental Math Money Multiplication Naming Numbers Patterns Percent Place Value Practical Math Properties Ratios Statistics Subtraction Math Resources Schools Teachers Parents Home Schooling Web Resources Spelling Lessons by Grade First Second Third Fourth Fifth Sixth Seventh Eighth or - Practice Your Word List Vocabulary Lessons by Grade First Second Third Fourth Fifth Sixth Seventh Eighth Geography States of the United States Nations of the World Geographical Photos Return to Top About This Site Frequently Asked Questions Send Us Feedback About this Site Privacy Policy Share| Return to Top