If (5t + 3u) : (5t — 3u) = 5 : 3, then what is the value of t : u?
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Correct answer: A
Explanation
The correct answer is option 3 i.e. 12 : 5.
(5t + 3u)(5t − 3u) = 5/3
⇒ 3(5t + 3u) = 5(5t − 3u)
⇒ 3 × 5t + 3 × 3u = 5 × 5t − 5 × 3u
⇒ 15t + 9u = 25t − 15u
⇒ 15t − 25t = −15u − 9u
⇒ −10t = −24u
⇒ t/u = -24/-10
⇒ t/u = 12/5