WAEC 2010 Mathematics · Question 16

The sum of 6 and one-third of x is one more than twice x, find x

Options

  1. A.x = 7
  2. B.x = 5
  3. C.x = 3
  4. D.x = 2

Answer: C. x = 3

Explanation written with AI and checked against the answer key

Analyze the question: We translate the words into an equation.

  • "The sum of 6 and one-third of x" → 6 + x/3
  • "is one more than twice x" → 2x + 1

Equation: 6 + x/3 = 2x + 1

Solve step by step:

  1. Multiply every term by 3 to remove the fraction: 18 + x = 6x + 3
  1. Collect like terms (move x to the right, numbers to the left): 18 − 3 = 6x − x
  1. Simplify: 15 = 5x
  1. Divide by 5: x = 3

Check:

  • Left side: 6 + 3/3 = 6 + 1 = 7
  • Right side: 2(3) + 1 = 7 ✓

Both sides are equal, so x = 3 is correct.

Tip: Whenever you see a fraction in an equation, multiply every term by the denominator to clear it first. Then always substitute your answer back to confirm. It takes just a few seconds and saves marks.

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