Which expression is equivalent to the fraction with numerator 15 A to the 8th power b to the 4th power and denominator 5 A to the 4th power b ?

Divide the coefficients: 15 ÷ 5 = 3. When dividing powers with the same base, subtract the exponents: A⁸ ÷ A⁴ = A⁴ and b⁴ ÷ b = b³, so the expression simplifies to 3A⁴b³, choice A.

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