Da VIP Academy / GED / Math / Ratios & Proportional Reasoning
Percent Applications
Solve discount, tax, tip, markup, and percent-change problems.
How it works
Discount and tax
A 25% discount leaves you paying 75%: $80 × 0.75 = $60. Tax adds on: an 8% tax means multiply by 1.08.
Percent change
Percent change = (new − old) ÷ old × 100. Going from 40 to 50 is 10 ÷ 40 = 25% increase.
Worked examples
A $46 bill with a 20% tip. What is the tip?
- 10% of 46 is 4.60.
- Double it for 20%.
- Tip = $9.20.
Words to know
- Percent change
- How much a value grew or shrank relative to the original.
Test-day tips
- • Discount problems are faster if you multiply by what is left, not by the discount.