5 pencils, 6 notebooks and 7 erasers cost ₹250; whereas 6 pencils, 4 notebooks and 2 erasers cost ₹180. What is the cost of 2 notebooks and 4 erasers?

Explanation

Let costs be p, n, e. We have 5p + 6n + 7e = 250 (1) and 3p + 2n + e = 90 (2). Multiply (1) by 3: 15p + 18n + 21e = 750. Multiply (2) by 5: 15p + 10n + 5e = 450. Subtracting gives 8n + 16e = 300 \implies 2n + 4e = 75.

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