Divide: 15a2b÷5ab2\dfrac{15a^2}{b} \div \dfrac{5a}{b^2}b15a2÷b25a.
3ab3ab3ab
3ab\dfrac{3a}{b}b3a
3a2b3a^2 b3a2b
3ba\dfrac{3b}{a}a3b