Question

A man buys 5 books and 10 pens for Rs. 3600.If he sells books at 25%profit and pens at 5%loss.And overall his profit is Rs.540. Find the cost price of books and pens?

Answer 1

Answer:

Cost of one book = 480

Cost of one pen = 120

Step-by-step explanation:

$let \: the \: cost \: of \:a \: book\: be \: x \: and \: pen \: be \: y \\ \\ = > 5x + 10y = 3600 \\ \\ = > x + 2y = 720... < 1 > \\ \\ {x}^{l} = x + \frac{25}{100} x = 1.25x\\ \\ {y}^{l} = y - \frac{5}{100} y = 0.95y\\ \\ given \\ \\ 5x + 10y + 540 = 5 {x}^{l} + 10 {y}^{l} \\ \\ = > 6.25x + 9.5y = 5x + 10y + 540 \\ \\ = > 1.25x - 0.5y = 540 \\ \times 4\\ = > 5x - 2y = 2160... < 2 > \\ \\ < 1 > + < 2 > \\ \\ (x + 2y) + (5x - 2y) = 720 + 2160 \\ \\ 6x = 2880 \\ \\ = > x = 480 \\ \\ = > y = 120$

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