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प्रश्न
3 bags and 4 pens together cost Rs 257 whereas 4 bags and 3 pens together cost R 324.
Find the total cost of 1 bag and 10 pens.
उत्तर
Let the cost of a bag be Rs x and that of a pen be Rs y. Then,
3x + 4y = 257 ...(i)
4x + 3y = 324 ....(ii)
Multiplying equation (i) by 3 and equation (ii) by 4, we get
9x + 12y = 770 ...(iii)
16x + 12y = 1296 ....(iv)
Subtracting equation (iii) by equation (iv), we get
16x + 9x = 1296 - 771
=> 7x = 525
`=> x = 525/7 = 75`
Cost of a bag = Rs 75
Putting x = 75 in equation (i), we get
`3 xx 75 + 4y = 257`
=> 225 + 4y = 257
=> 4y = 257 - 225
=> 4y = 32
`=> y = 32/4 = 8`
∴Cost of a pen = Rs 8
∴ Cost of 10 pens = 8 xx 10 = Rs 80
Hence, the total cost of 1 bag and 10 pens = 75 + 80 = Rs 155
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