b) $4\\frac{1}{2} \\div \\frac{1}{4}$

$b) $4\\frac{1}{2} \\div \\frac{1}{4}$$

b) $4\frac{1}{2} \div \frac{1}{4}$

$4\frac{1}{2} = \frac{4\times2 + 1}{2} = \frac{9}{2}$

$\frac{9}{2} \div \frac{1}{4} = \frac{9}{2} \times \frac{4}{1}$

$\frac{9\times4}{2\times1} = \frac{36}{2}$

$\frac{36}{2} = 18$

18