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

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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

Solve for X:

\( 3x=18 \)

FAQ

Everything you need to know about this question

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

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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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