Example :
A store sells large and small sizes of blue shirts and yellow shirts. The selling price of either shirt is $x for a large size and $y for a small size. The table shows the number of shirts sold in a day.
large |
small |
|
blue shirt |
5 |
3 |
yellow shirt |
6 |
4 |
The total income from the sale of the blue shirt was $84 and from the yellow shirt was $104.
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a) Write down an equation connecting A, B and C
b) Find A-1
c) Calculate A -1C
d) Explain the significance of your answer to part (c)
Solution:
a) AB = C
b) Determinant = (5 × 4) – (3 × 6) = 2
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c) ![]()
d) The answers in part (c) are the answers for the matrix B.

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So, cost of large size shirt (x) = $12
cost of small size shirt (y) = $8
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