CurriculumGrade 9Mathematics

Writing One-Variable Equations

Aligned to A-CED.A.1 — Common Core State Standards for Mathematics.

What this lesson teaches

Translate a word problem into an equation by naming the unknown and writing the relationship with symbols, then solve for the unknown.

Worked example

A phone plan costs $30 plus $0.10 per text. If the bill is $45, how many texts? Write 30 + 0.10t = 45. Subtract 30: 0.10t = 15. Divide by 0.10: t = 150 texts.

Practice questions

  1. A number tripled and increased by 4 is 25. Write and solve an equation.
  2. Tickets cost $8 each. Write and solve an equation for how many tickets cost $96.
  3. You need at least 90 points and have 72, with each task worth 6. Write and solve an inequality for the tasks needed.

Watch the lesson

Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.

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En español

Escribir Ecuaciones de una Variable

Traduce un problema verbal a una ecuación nombrando la incógnita y escribiendo la relación con símbolos; luego resuelve para la incógnita.

Ejemplo: Un plan de celular cuesta $30 más $0.10 por mensaje. Si la cuenta es $45, ¿cuántos mensajes? Escribe 30 + 0.10t = 45. Resta 30: 0.10t = 15. Divide entre 0.10: t = 150 mensajes.

More Algebra lessons

Solving Linear Equations and InequalitiesA-REI.B.3Solving Quadratic Equations by FactoringA-REI.B.4Parts of an ExpressionA-SSE.A.1Rewriting by StructureA-SSE.A.2Equivalent Forms of ExpressionsA-SSE.B.3Operations with PolynomialsA-APR.A.1

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