Solve Linear Equation: Finding Survey Size Using 8x+4 and Fractions

Linear Equations with Mixed Fractions

The number of respondents to a survey is 8x+4 8x+4 .


23 \frac{2}{3} of them and another 2x 2x responded that they do not like pistachio ice cream, while the remaining 8 participants said that they really liked the flavor.

How many participants were there in the survey?

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Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

The number of respondents to a survey is 8x+4 8x+4 .


23 \frac{2}{3} of them and another 2x 2x responded that they do not like pistachio ice cream, while the remaining 8 participants said that they really liked the flavor.

How many participants were there in the survey?

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Write an equation based on the information given.
  • Step 2: Simplify and solve for x x .
  • Step 3: Compute the total number of participants using the value of x x .

Step 1: Set up the equation:

23(8x+4)+2x+8=8x+4 \frac{2}{3}(8x + 4) + 2x + 8 = 8x + 4

Step 2: Simplify the equation:

First, calculate 23(8x+4) \frac{2}{3}(8x + 4) :

238x+234=16x3+83 \frac{2}{3} \cdot 8x + \frac{2}{3} \cdot 4 = \frac{16x}{3} + \frac{8}{3}

Insert this back into the equation:

16x3+83+2x+8=8x+4 \frac{16x}{3} + \frac{8}{3} + 2x + 8 = 8x + 4

Multiply the entire equation by 3 to eliminate the fractions:

16x+8+6x+24=24x+12 16x + 8 + 6x + 24 = 24x + 12

Simplify:

22x+32=24x+12 22x + 32 = 24x + 12

Reorganize the equation:

22x+3222x=24x+1222x 22x + 32 - 22x = 24x + 12 - 22x

32=2x+12 32 = 2x + 12

Solve for x x :

3212=2x 32 - 12 = 2x

20=2x 20 = 2x

x=10 x = 10

Step 3: Calculate the total number of participants:

Substitute x=10 x = 10 into 8x+4 8x + 4 :

8(10)+4=80+4=84 8(10) + 4 = 80 + 4 = 84

Therefore, the total number of participants is 84.

3

Final Answer

84

Key Points to Remember

Essential concepts to master this topic
  • Setup: Translate word problem into equation using given expressions
  • Technique: Multiply entire equation by 3 to eliminate fractions: 16x3 \frac{16x}{3} becomes 16x
  • Check: Substitute x = 10 back: 23(84)+20+8=84 \frac{2}{3}(84) + 20 + 8 = 84

Common Mistakes

Avoid these frequent errors
  • Not setting up the correct equation from word problem
    Don't just use the expressions without understanding the total = wrong equation setup! Students often miss that the three groups (fraction who dislike, additional 2x who dislike, and 8 who like) must add up to the total survey size. Always identify what equals what before writing the equation.

Practice Quiz

Test your knowledge with interactive questions

Find the value of the parameter X

\( \frac{1}{3}x=\frac{1}{9} \)

FAQ

Everything you need to know about this question

How do I know what should equal what in the word problem?

+

The key is identifying the total. Here, the total survey size is 8x+4 8x + 4 , and all respondents must add up to this total: those who don't like it plus those who do like it.

Why do we multiply the whole equation by 3?

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Multiplying by 3 clears the fraction 23 \frac{2}{3} and makes the equation easier to solve. Remember to multiply every single term on both sides by 3!

What if I get a different value for x?

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Double-check your algebra steps! Common errors include forgetting to distribute the 23 \frac{2}{3} properly or making arithmetic mistakes when combining like terms.

How can I verify my final answer makes sense?

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Check that all groups add up: 56 people don't like it (2/3 of 84 = 56), 20 more don't like it (2x = 20), and 8 like it. Total: 56 + 20 + 8 = 84 ✓

Why is the fraction 2/3 of the total group?

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The problem says 23 \frac{2}{3} of all respondents and another 2x don't like pistachio. So it's 2/3 of the entire survey size 8x+4 8x + 4 , not just part of it.

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