Mathematics
Drawing pencils cost ₹ 4 each and coloured pencils cost ₹ 5.50 each. If altogether two dozen pencils cost ₹108, how many coloured pencils are there?
Linear Equations
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Answer
Let number of drawing pencils be x and number of coloured pencils be y.
Total pencils = 24 (two dozens).
⇒ x + y = 24
⇒ x = 24 - y ………………….(1)
Cost of drawing pencils = ₹ 4 each
Total cost of drawing pencils = ₹4x
Cost of coloured pencils = ₹ 5.50 each
Total cost of coloured pencils = ₹5.50y
Total cost = ₹ 108
⇒ 4x + 5.50y = 108
Substituting the value of x from equation (1), we get
⇒ 4(24 - y) + 5.50y = 108
⇒ 96 - 4y + 5.50y = 108
⇒ 96 + 1.5y = 108
⇒ 1.5y = 108 - 96
⇒ 1.5y = 12
⇒ y =
⇒ y = 8.
Hence, number of coloured pencils = 8.
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