Answer
$48\text{ ounces}$
Work Step by Step
Use the conversion rate $1 \text{pound} = 16 \text{ ounces}$ by multiplying $\frac{16\text{ ounces}}{1\text{ pound}}$ to obtain:
$\require{cancel}
3\text{ lb}
\\= 3\text{ lb} \cdot \frac{16\text{ ounces}}{1\text{ lb}}
\\= 3\cancel{\text{ lb}} \cdot \frac{16\text{ ounces}}{1\cancel{\text{ lb}}}
\\=48\text{ ounces}$
