Solve for X: 5.4x + 1/5 - 3/10 = 6.4x - 2/5 Linear Equation

Linear Equations with Mixed Decimal-Fraction Terms

Solve for X:

5.4x+15310=6.4x25 5.4x+\frac{1}{5}-\frac{3}{10}=6.4x-\frac{2}{5}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:05 Collect terms
00:14 Arrange the equation so that one side has only the unknown X
00:37 Collect terms
00:43 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve for X:

5.4x+15310=6.4x25 5.4x+\frac{1}{5}-\frac{3}{10}=6.4x-\frac{2}{5}

2

Step-by-step solution

To solve this problem, we will follow these steps:

  • Step 1: Move all terms involving x x to one side of the equation and constants to the other.
  • Step 2: Solve for x x by simplifying both sides.
  • Step 3: Identify the solution among the given choices.

Let's begin:

Step 1: Move the terms involving x x to one side of the equation:

5.4x+15310=6.4x25 5.4x + \frac{1}{5} - \frac{3}{10} = 6.4x - \frac{2}{5}

Subtract 5.4x 5.4x and add 25 \frac{2}{5} to both sides:

15310+25=6.4x5.4x \frac{1}{5} - \frac{3}{10} + \frac{2}{5} = 6.4x - 5.4x

Simplify:

Step 2: Combine like terms:

The left side becomes:

15+25310 \frac{1}{5} + \frac{2}{5} - \frac{3}{10}

Convert fractions to have the same denominator:

  • 15=210 \frac{1}{5} = \frac{2}{10}
  • 25=410 \frac{2}{5} = \frac{4}{10}

Combine the terms:

210+410310=310 \frac{2}{10} + \frac{4}{10} - \frac{3}{10} = \frac{3}{10}

The right side becomes:

1x=x 1x = x

Step 3: Set the simplified terms equal to each other:

310=x \frac{3}{10} = x

Therefore, the solution to the problem is x=310 x = \frac{3}{10} , which corresponds to choice .

3

Final Answer

310 \frac{3}{10}

Key Points to Remember

Essential concepts to master this topic
  • Strategy: Move all x terms to one side, constants to the other
  • Technique: Convert fractions to same denominator: 15=210 \frac{1}{5} = \frac{2}{10} , 25=410 \frac{2}{5} = \frac{4}{10}
  • Check: Substitute x=310 x = \frac{3}{10} back: 5.4(310)+15310=6.4(310)25 5.4(\frac{3}{10}) + \frac{1}{5} - \frac{3}{10} = 6.4(\frac{3}{10}) - \frac{2}{5}

Common Mistakes

Avoid these frequent errors
  • Forgetting to convert decimals and fractions consistently
    Don't mix 5.4x with fractions without converting = calculation errors! Students often add 15310 \frac{1}{5} - \frac{3}{10} incorrectly by not finding common denominators. Always convert all fractions to the same denominator before combining terms.

Practice Quiz

Test your knowledge with interactive questions

Solve for X:

\( x - 3 + 5 = 8 - 2 \)

FAQ

Everything you need to know about this question

Should I convert decimals to fractions or fractions to decimals?

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Either works! For this problem, keeping fractions as fractions is easier since we need to add 15310+25 \frac{1}{5} - \frac{3}{10} + \frac{2}{5} . Converting to common denominators makes the arithmetic cleaner.

How do I subtract 5.4x from 6.4x correctly?

+

Think of it as 6.4x5.4x=(6.45.4)x=1.0x=x 6.4x - 5.4x = (6.4 - 5.4)x = 1.0x = x . The coefficient of x becomes 1, which we usually just write as x.

Why is my final answer a simple fraction?

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Linear equations often have fractional solutions! The answer x=310 x = \frac{3}{10} is already in simplest form since 3 and 10 share no common factors.

What if I can't find a common denominator easily?

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For fifths and tenths, remember that 10 is a multiple of 5. So tenths (10) is your LCD. Convert: 15=210 \frac{1}{5} = \frac{2}{10} and 25=410 \frac{2}{5} = \frac{4}{10} .

How do I verify my answer is correct?

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Substitute x=310 x = \frac{3}{10} into the original equation. Calculate each side separately: Left side = 5.4(310)+15310 5.4(\frac{3}{10}) + \frac{1}{5} - \frac{3}{10} and Right side = 6.4(310)25 6.4(\frac{3}{10}) - \frac{2}{5} . Both should equal the same value!

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