Percent Problems: Tax, Markup & Discount
Aligned to 7.RP.A.3 — Common Core State Standards for Mathematics.
What this lesson teaches
Many percent problems use part = percent × whole. For tax or a markup, find the percent amount and add it; for a discount, subtract it. Percent change = (change ÷ original) × 100.
Worked examples
Example 1
A $40 jacket is discounted 25%. Discount = 0.25 × 40 = $10. Sale price = 40 − 10 = $30.
Example 2
A $60 meal with 18% tip: tip = 0.18 × 60 = $10.80, total = $70.80. Or multiply once: 1.18 × 60 = $70.80.
Example 3
A 20% discount followed by 20% tax does not return the original price. $100 → $80 → $96, because each percent applies to a different amount.
Practice questions
- A $60 item has 8% sales tax. What is the total cost?
- A store marks up a $25 shirt by 40%. Find the new price.
- A stock rose from $50 to $65. What is the percent change?
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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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Problemas de Porcentaje: Impuesto, Aumento y Descuento
Muchos problemas de porcentaje usan parte = porcentaje × total. Para un impuesto o aumento, calcula el porcentaje y súmalo; para un descuento, réstalo. Cambio porcentual = (cambio ÷ original) × 100.
Ejemplo 1: Una chamarra de $40 tiene 25% de descuento. Descuento = 0.25 × 40 = $10. Precio de oferta = 40 − 10 = $30.
Ejemplo 2: Una comida de $60 con 18% de propina: propina = 0.18 × 60 = $10.80, total = $70.80. O multiplica una vez: 1.18 × 60 = $70.80.
Ejemplo 3: Un descuento de 20% seguido de 20% de impuesto no regresa al precio original. $100 → $80 → $96, porque cada porcentaje se aplica a una cantidad distinta.
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