Explanation:
To divide by a fraction, multiply by its reciprocal.
1) (m² / 9) / (n² / m)
(m² / 9) × (m / n²)
m³ / (9n²)
2) (4 / y) / (2 / (yx))
(4 / y) × (yx / 2)
2x
3) (x² / y) / (1 / y)
(x² / y) × (y / 1)
x²
4) (3 / b) / (9 / a²)
(3 / b) × (a² / 9)
a² / (3b)
5) (x² / 16) / (16 / y²)
(x² / 16) × (y² / 16)
x²y² / 256