Question 11

A file and 3 identical pens cost $29.20. 2 such files and 8 such pens cost $76.20. What was the cost of 1 such pen? (4 marks)

Answer: $ 8.90

Workings

1 file + 3 pens = $29.20 (first equation) 2 files + 8 pens = $76.20 (second equation)

first, is to remove the 2 files

we can multiple the 1st equation by 2

1 file + 3 pens = $29.20 1 file + 3 pens = $29.20

2 files + 6 pens = $58.40 (third equation)

then we can minus from the 2nd equation

2 files + 8 pens = $76.20 2 files + 6 pens = $58.40 2 pens = 76.20 - 58.40

2 pens = $17.80 1 pen = 17.80 ÷ 2 = $8.90

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