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WAEC Mathematics 1991 (August) Question 9

Question 9

Algebraic Expressions

Simplify (3/x − 15/(2y)) ÷ 6/(xy)

  1. A.(2y − 5x)/4
  2. B.9(2x − 5x)/(x2y2)
  3. C.(5x − 2y)/2
  4. D.x2y2/(18y − 45x)
  5. E.4/(2y − 5x)
Show the answer and explanation

Answer: A ((2y − 5x)/4)

Explanation

3/x − 15/(2y) = (6y − 15x)/(2xy). Dividing by 6/(xy) means multiplying by xy/6: (6y − 15x)/12 = 3(2y − 5x)/12 = (2y − 5x)/4.