Solve Linear Relationships: Finding x When 8x-14 < 5x+4

Inequality Solutions with Contextual Constraints

Daniel has a number of sweets.

Mariano has 5 times plus 4 more sweets than Daniel

Iván has 8 times plus 14 fewer sweets than Daniel.

Iván has fewer sweets than Mariano.

What is the possible number of sweets that Daniel has in terms of x?

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1

Understand the problem

Daniel has a number of sweets.

Mariano has 5 times plus 4 more sweets than Daniel

Iván has 8 times plus 14 fewer sweets than Daniel.

Iván has fewer sweets than Mariano.

What is the possible number of sweets that Daniel has in terms of x?

2

Step-by-step solution

To solve this problem, we'll contemplate the mathematical relationships between the sweets.

  • Step 1: Expression Setup
    Mariano's sweets can be expressed as 5x+4 5x + 4 , and Iván's sweets are 8x14 8x - 14 .
  • Step 2: Inequality Setup
    Given that Iván has fewer sweets, establish an inequality: 8x14<5x+4 8x - 14 < 5x + 4 .
  • Step 3: Solve the Inequality
    Simplify the inequality:
    8x14<5x+4 8x - 14 < 5x + 4
    Subtract 5x 5x from both sides:
    3x14<4 3x - 14 < 4
    Add 14 to both sides:
    3x<18 3x < 18
    Divide by 3:
    x<6 x < 6
  • Step 4: Considering Logical Constraints
    Since sweets represent physical goods, x x must be positive. Therefore, x>0 x > 0 .
  • Step 5: Conclusion
    Combining these inequalities, 0<x<6 0 < x < 6 .

Therefore, the possible number of sweets that Daniel has is 0<x<6 0 < x < 6 .

3

Final Answer

0<x<6 0 < x < 6

Key Points to Remember

Essential concepts to master this topic
  • Setup: Translate word problem into mathematical inequality expression
  • Technique: Solve 8x - 14 < 5x + 4 by collecting like terms
  • Check: Apply real-world constraint x > 0 for final answer ✓

Common Mistakes

Avoid these frequent errors
  • Ignoring the physical constraint that x must be positive
    Don't solve 8x - 14 < 5x + 4 and stop at x < 6! This ignores that Daniel can't have negative sweets. Always consider real-world constraints: since x represents sweets, x > 0, giving final answer 0 < x < 6.

Practice Quiz

Test your knowledge with interactive questions

Solve the following inequality:

\( 3x+4 \leq 10 \)

FAQ

Everything you need to know about this question

Why can't x be negative if the math gives x < 6?

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Great question! While the inequality mathematically allows negative values, the context doesn't. Daniel can't have negative sweets! Always consider what the variable represents in real life.

How do I know which person has fewer sweets from the word problem?

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Look for key phrases like 'fewer than' or 'less than'. The problem states 'Iván has fewer sweets than Mariano,' so Iván's amount < Mariano's amount.

What if I set up the inequality backwards?

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If you write 5x+4<8x14 5x + 4 < 8x - 14 instead, you'll get x>6 x > 6 . Always double-check: does your answer make sense with the original constraint?

Can x equal exactly 6 in this problem?

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No! When x = 6, both Iván and Mariano have the same number of sweets (32 each). But the problem says Iván has fewer sweets, so x must be strictly less than 6.

Why is the answer 0 < x < 6 instead of just x < 6?

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Because context matters! The variable x represents the number of sweets Daniel has. Since you can't have negative sweets, we need x > 0. Combined with x < 6, we get 0 < x < 6.

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