A wet bed sheet on a line holds 350 g of water…

Step 1. The units. $350\ \text{g} = 0.35\ \text{kg}$, and $5\ \text{h} = 5 \times 3600\ \text{s} = 18\,000\ \text{s}$.

Step 2. (a) $Q = mL = 0.35\ \text{kg} \times 2.26 \times 10^{6}\ \text{J/kg} = 7.91 \times 10^{5}\ \text{J}$.

Step 3. (b) $P = \dfrac{7.91 \times 10^{5}\ \text{J}}{18\,000\ \text{s}} = 43.9\ \text{W}$.