What is the quotient? the fraction with numerator A minus 3 and denominator 7 divided by the fraction with numerator 3 minus A and denominator 21

Divide by the second fraction by multiplying by its reciprocal: \(\frac{A-3}{7}\times\frac{21}{3-A}\). Since \(3-A=-(A-3)\), the factors involving \(A-3\) cancel with a negative sign, and \(21/7=3\), giving \(-3\) (for \(A\ne3\), so the original divisor is not zero). The correct choice is negative 3.

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