Write and Solve Equations Using Addition or Subtraction

6.AT.8 · Unit 8 · Lesson 2

Name   Period

Objectives / Objetivos

Content Objective: I can solve one-step addition and subtraction equations using inverse operations.

Language Objective: I can explain my steps using the words equation, inverse operation, isolate, and solution.

Key Idea / Idea clave

Solving Addition & Subtraction Equations. Formula: x + a = b → x = b − a | x − a = b → x = b + a. 1. Identify operation on variable. 2. Use inverse operation: subtract to undo addition; add to undo subtraction. 3. Property of Equality: do same operation to both sides.

I Notice / Observo

  • What operation connects the locker number and 23?
  • What does n represent in the equation?

I Wonder / Me pregunto

  • What if the message said 'the number minus 23 equals 58' instead?

Vocabulary / Vocabulario

Term / TérminoDefinition / Definición
Solve One-Step Addition and Subtraction Equations
Resolver ecuaciones de suma y resta de un paso		Use one inverse addition or subtraction operation to isolate the variable.
Usar una operación inversa de suma o resta para aislar la variable.
Equation
Ecuación		A math sentence with an equal sign showing both sides are the same.
Una oración matemática con un signo igual que muestra que ambos lados son iguales.
Inverse operation
Operación inversa		Two math actions that undo each other, like × and ÷.
Dos operaciones que se deshacen entre sí, como × y ÷.
Isolate
Despejar		To get the letter by itself on one side.
Dejar la letra sola en un lado.
Solution
Solución		A number that makes the equation or inequality true.
Un número que hace verdadera la ecuación o desigualdad.
One-step equation
Ecuación de un paso		An equation you can solve in a single step using one inverse operation.
Una ecuación que puedes resolver en un solo paso usando una operación inversa.

Practice Preview / Vista previa de práctica

  1. Solve: x + 9 = 15
    1. x = 6
    2. x = 24
    3. x = 9
    4. x = 15
  2. Solve: m − 14 = 32
  3. Complete the table: identify the inverse operation, solve, and check.
  4. Find the Equation Error
    1. Step 1: Equation — x − 18 = 45
    2. Step 2: Identify inverse — Inverse of subtraction is subtraction
    3. Step 3: Apply to both sides — x − 18 − 18 = 45 − 18
    4. Step 4: Simplify — x = 27

    Which step has the mistake? Explain it and write the correct work.

Reflection / Reflexión

One thing I learned today / Una cosa que aprendí hoy: