Creating Equations to Model Problems
Aligned to A-CED.A.1 — Common Core State Standards for Mathematics.
What this lesson teaches
Translate a real situation into an equation or inequality by naming the unknown, then writing how the quantities relate. Solving the equation answers the question the situation asks.
Worked example
A gym charges a $50 signup fee plus $30 per month. When does the total cost reach $200? Model it as 50 + 30m = 200. Subtract 50: 30m = 150. Divide by 30: m = 5 months.
Practice questions
- A phone plan costs $20 plus $0.10 per text. Write an equation for a $35 bill.
- You save $15 each week toward a $180 goal. Write and solve an equation for the number of weeks.
- Write an inequality: a car rental is $40 plus $0.25 per mile and must stay under $100.
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.
▶ Watch this lessonEn español
Crear Ecuaciones para Modelar Problemas
Traduce una situación real a una ecuación o desigualdad nombrando la incógnita y luego escribiendo cómo se relacionan las cantidades. Resolver la ecuación responde lo que la situación pregunta.
Ejemplo: Un gimnasio cobra una inscripción de $50 más $30 por mes. ¿Cuándo llega el costo total a $200? Modélalo como 50 + 30m = 200. Resta 50: 30m = 150. Divide entre 30: m = 5 meses.
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