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    Question

    If (10 a³ + 4b³): (11a³ — 15b³) = 7:5, then (3a +

    5b): (9a - 2b) = ?
    A 10:13 Correct Answer Incorrect Answer
    B 8 :7 Correct Answer Incorrect Answer
    C 5 :4 Correct Answer Incorrect Answer
    D 3:2 Correct Answer Incorrect Answer

    Solution

    10a3 + 4b3 /11a3  – 15b3  = 7/5 =50a3  +20b3 = 77a3 -105b3 = 27a3  = 125b3  = a3  / b3  = 125/27 = a/b = 5/3 = (3a + 5b) / (9a – 2b) = 3 × 5 + 5 × 3 / 9 × 5 – 2 × 6 = 30/39 = 10 : 13

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