Calculating the New Price After Discount

When a shirt costs $20 and is on sale for 15% off, the new price can be calculated using the formula:

[ \text{New Price} = \text{Original Price} - (\text{Original Price} \times \text{Discount Rate}) ]

Substituting the values, we get:

[ \text{New Price} = 20 - (20 \times 0.15) = 20 - 3 = $17. ]

Therefore, the new price of the shirt after a 15% discount is $17. Students in Grade 7 can utilize this formula to understand percent decrease and apply it to real-life scenarios.