Example

Solving a Tip Calculation Using a Percent Equation

Apply the seven-step problem-solving strategy to a percent application in which the amount (the tip) is the unknown.

Problem: Dezohn's restaurant bill was $68.50, and he wants to leave an 18%18\% tip. How much should the tip be?

  1. Identify what to find: the dollar amount of the tip.
  2. Name the unknown: Let tt = the tip amount.
  3. Translate into a percent sentence and equation: "The tip is 18%18\% of the total bill" becomes

t=0.18×68.50t = 0.18 \times 68.50

  1. Solve by multiplying:

t=12.33t = 12.33

  1. Check — a quick reasonableness test: 20%20\% of $70 would be $14, so $12.33 for 18%18\% of $68.50 is sensible.
  2. Answer: Dezohn should leave a tip of $12.33.

This problem is a "find the amount" percent equation — the percent and the base are both known, so the variable is already isolated after translation and only a single multiplication step is needed. Choosing the letter tt (for "tip") makes the equation easier to read and interpret in context.

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Updated 2026-04-24

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