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Word problemsArithmeticMiddle schoolabout 0:57

A number decreased by 15% is 68. What is the number?: animated lesson

A narrated, step-by-step word problems video lesson with captions. Final answer: The number is 80.

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Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.3 MB) · Captions (WebVTT)

Steps on screen

1. The problem
Worked example
A number decreased by 15% is 68. What is the number?
2. Step by step
1. Read the problem
2. Solve the linear equation
3. The answer
$\text{The number is 80}$
The number is 80
4. Check
- Substitute x = 80: (80) *(1-15/100) = 68 ✓

Transcript

The problem. Here is the problem: A number decreased by 15 percent is 68. What is the number? Let x be the number: “a number decreased by 15 percent” becomes x times (1 minus 15 over 100).

Step by step. Read the problem. Let x be the unknown number. “a number decreased by 15 percent is 68” translates to x times (1 minus 15 over 100) equals 68. Solve the linear equation. 0.85x plus 0 equals 68 → x equals (68 minus 0) / 0.85 equals 80.

The answer. So the answer is The number is 80. Let x be the number: “a number decreased by 15 percent” becomes x times (1 minus 15 over 100).

Check. Substitute x equals 80: (80) times (1 minus 15 over 100) equals 68, which checks out.

About word problems

Turn everyday situations about prices, speed, ages and interest into equations and solve them.

A number decreased by 15% is 68. What is the number?