If 3p = 4q and 9p = 8q - 12, find the value of pq.

  • A 12
  • B 7
  • C -7
  • D -12
waec 2019mathematics

The correct answer is A. 12

9p = 8q - 12

9p = 2(4q) - 12

9p = 2(3q) - 12

9p = 6p - 12

3p = -12 

p = -4

\(\frac{3 \times -4}{4} = \frac{4q}{4}\) 

q = 13

pq = -3 x -4 

= 12

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