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Question
If 7x – 15y = 4x + y, find the value of x : y. Hence, use componendo and dividendo to find the values of:
`(9x + 5y)/(9x - 5y)`
Solution
7x – 15y = 4x + y
7x – 4x = y + 15y
3x = 16y
`x/y = 16/3`
`=> (9x)/(5y) = 144/15` ...`("Multiplying both sides by" 9/5)`
`=> (9x + 5y)/(9x - 5y) = (144 + 15)/(144 - 15)` ...(Applying componendo and dividendo)
`=> (9x + 5y)/(9x - 5y) = (159)/(129) = 53/43`
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