Question:

If \(x:y=4:5\), then \((5x+4y):(10x-2y)=\ ?\)

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When a ratio \(a:b\) is given, replace the quantities by \(ak\) and \(bk\). This simplifies ratio problems considerably.
Updated On: Jun 12, 2026
  • \(1:2\)
  • \(3:4\)
  • \(4:3\)
  • \(5:4\)
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The Correct Option is C

Solution and Explanation

Concept: Whenever a ratio of two quantities is given, we may assume the quantities to be proportional to the terms of the ratio. Given: \[ x:y=4:5 \] Let \[ x=4k,\qquad y=5k \] where \(k\) is a non-zero constant.

Step 1:
Substitute the values into the first expression. \[ 5x+4y \] \[ =5(4k)+4(5k) \] \[ =20k+20k \] \[ =40k \]

Step 2:
Substitute the values into the second expression. \[ 10x-2y \] \[ =10(4k)-2(5k) \] \[ =40k-10k \] \[ =30k \]

Step 3:
Form the required ratio. \[ (5x+4y):(10x-2y) = 40k:30k \] Cancelling the common factor \(10k\), \[ =4:3 \] Therefore, \[ \boxed{4:3} \]
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