Question
Download Solution PDFThe cost of 5 notebooks and 4 pens is ₹ 142. The cost of 7 notebooks and 3 pens is ₹ 28 less than the cost of 9 notebooks and 1 pen. What is the cost of 4 notebooks and 5 pens?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
5 notebooks + 4 pens = ₹142
7 notebooks + 3 pens = 9 notebooks + 1 pen - ₹28
Formula used:
Form and solve linear equations.
Calculation:
Let the cost of one notebook be 'n' and the cost of one pen be 'p'.
Then,
5n + 4p = 142 ... (1)
Also,
7n + 3p = 9n + p - 28
7n + 3p - 9n - p = -28
-2n + 2p = -28
-n + p = -14
p = n - 14 ... (2)
Substitute equation (2) into equation (1):
5n + 4(n - 14) = 142
5n + 4n - 56 = 142
9n = 142 + 56
9n = 198 = 198 / 9
n = 22
Substitute n = 22 into equation (2):
p = 22 - 14
p = 8
Now the cost of 4 notebooks and 5 pens:
4n + 5p = 4 × 22 + 5 × 8
4n + 5p = 88 + 40
4n + 5p = 128
∴ The cost of 4 notebooks and 5 pens is ₹128.
Last updated on Apr 24, 2025
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