Solve for the variable: addition, subtraction, multiplication, and division

Learning Objectives Identify the unknown value (variable) in a one-step equation. Solve for a variable in an addition equation using subtraction. Solve for a variable in a subtraction equation using addition. Solve for a variable in a multiplication equation using division. Solve for a variable in a division equation using multiplication. Verify their solution by substituting the value back into the original equation. If you have 10 candies and your friend gives you some more, and now you have 18, how many did your friend give you? 🍬 You just solved for a variable! In this lesson, you will become a math detective! We will learn how to find the value of a 'mystery number,' called a variable, in an equation. Using special 'opposite' operations is the key...

TermDefinitionExample VariableA letter or symbol that stands for an unknown number or a 'mystery number' in an equation.In the equation `n + 7 = 15`, the letter `n` is the variable. EquationA mathematical sentence stating that two things are equal. It must have an equals sign (=).`4 + 5 = 9` is an equation. Inverse OperationsOperations that 'undo' each other. They are opposites that work in pairs.Addition and subtraction are inverse operations. Multiplication and division are also inverse operations. SolutionThe value of the variable that makes an equation true.In `x + 3 = 10`, the solution is `x = 7` because `7 + 3 = 10`. Balance the EquationThe rule that whatever you do to one side of an equation, you must do the exact same thing to the other side to keep it equal.To...

The Balancing Rule for Addition and Subtraction If $a = b$, then $a + c = b + c$ and $a - c = b - c$. To find the variable, you can add or subtract the same number from both sides of the equation. Use the inverse operation to get the variable by itself. The Balancing Rule for Multiplication and Division If $a = b$, then $a \times c = b \times c$ and $a \div c = b \div c$ (where $c \neq 0$). To find the variable, you can multiply or divide both sides of the equation by the same non-zero number. Use the inverse operation to isolate the variable.