Q. If a : b = 7 : 9 and b : c = 15 : 7, then what is a : c?
Answer: 5 : 3
Notes: a : c = (a : b) $latex \times$ (b : c) $latex = \frac{7}{9}\times \frac{15}{7} = \frac{15}{9} = 5 : 3&s=1$ Hence option [C] is the right answer

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