Question: Arelli bought a bike for $80. After using it for a few months, she decided to sell it used for 20% less. How much did she sell the bike for? Identify and label the point on the double number line that represents the original price of the bike.
Savings (dollars)
0
0%
20%
40%
60%
80%
100%
120%
Graph: a double number line with Savings (dollars) on the top line and percent on the bottom line; the point for the original price is at 100% on the bottom line, corresponding to 80 dollars on the top line. position_hint=center
1. **State the problem:** Arelli bought a bike for $80 and sold it for 20% less. We need to find the selling price.
2. **Formula used:** To find the selling price after a percentage decrease, use:
$$\text{Selling Price} = \text{Original Price} - \text{Decrease Amount}$$
where
$$\text{Decrease Amount} = \text{Original Price} \times \frac{\text{Percentage Decrease}}{100}$$
3. **Calculate the decrease amount:**
$$\text{Decrease Amount} = 80 \times \frac{20}{100} = 80 \times 0.20 = 16$$
4. **Calculate the selling price:**
$$\text{Selling Price} = 80 - 16$$
Show canceling step:
$$\text{Selling Price} = \cancel{80} - \cancel{16} + (80 - 16) = 64$$
5. **Answer:** Arelli sold the bike for $64.
6. **Double number line explanation:** The original price corresponds to 100% on the percent line and $80 on the savings (dollars) line. The selling price is 80% of the original price (100% - 20%), which corresponds to $64 on the savings line.