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DecimalsArithmeticElementary schoolabout 0:52

Calculate 0.3x = 0.9: animated lesson

A narrated, step-by-step decimals video lesson with captions. Final answer: x = 3.

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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
Solving an equation
$0.3~ x = 0.9$
2. Step by step
1. $0.3~ x = 0.9$
  Start with the equation
2. $\frac{3}{10}x = \frac{9}{10}$
  Simplify each side (distribute and combine like terms)
3. $x = \frac{9}{10} \div \frac{3}{10} = 3$
  Divide both sides by 3/10 (multiply by its reciprocal)
3. On the graph
Each solution is where the graph of left side minus right side crosses zero.
4. The answer
$x = 3$
x = 3
5. Check
- x = 3: left side = 0.9, right side = 0.9 ✓

Transcript

The problem. Here is the problem: 0.3x equals 0.9. A linear equation in x: isolate x using inverse operations.

Step by step. Start with the equation. Simplify each side (distribute and combine like terms). Divide both sides by 3 over 10 (multiply by its reciprocal).

On the graph. Now look at the graph of the left side minus the right side. It crosses zero exactly at the solutions we found.

The answer. So the answer is x equals 3. Doing the same operation to both sides keeps the equation balanced. Undoing addition, then multiplication, leaves x alone.

Check. x equals 3: left side equals 0.9, right side equals 0.9, which checks out.

About decimals

Add, subtract, multiply and divide decimal numbers, keeping track of the decimal point.

Calculate 0.3x = 0.9: Decimals Step-by-Step Lesson