To write the decimal 0.45 as a fraction.

The decimal 0.45 has two digits after the decimal point, so it can be written as 45 over 100.

$$0.45 = \frac{45}{100}$$

Both 45 and 100 are divisible by 5.

$$\frac{45 \div 5}{100 \div 5} = \frac{9}{20}$$

The fraction cannot be simplified further.

The decimal 0.45 as a fraction is:

$$\boxed{\frac{9}{20}}$$

:
The question asks to calculate the total money spent daily by the motorist.

The motorcycle covers a distance of $40 \text{ km}$ daily.
It consumes $1 \text{ litre}$ of petrol for every $9 \text{ km}$.
To find the total litres consumed, divide the total distance by the distance covered per litre.

$$\text{Litres consumed} = \frac{\text{Total distance}}{\text{Distance per litre}}$$ $$\text{Litres consumed} = \frac{40 \text{ km}}{9 \text{ km/litre}}$$ $$\text{Litres consumed} = \frac{40}{9} \text{ litres}$$

The cost per litre of petrol is $\text{Sh. } 160$.
To find the total cost, multiply the total litres consumed by the cost per litre.

$$\text{Total cost} = \text{Litres consumed} \times \text{Cost per litre}$$ $$\text{Total cost} = \frac{40}{9} \text{ litres} \times 160 \text{ Sh./litre}$$ $$\text{Total cost} = \frac{40 \times 160}{9} \text{ Sh.}$$ $$\text{Total cost} = \frac{6400}{9} \text{ Sh.}$$

$$\text{Total cost} = 711.111... \text{ Sh.}$$

Rounding to two decimal places:

$$\text{Total cost} \approx 711.11 \text{ Sh.}$$

The motorist spends daily:

$$\boxed{\text{Sh. } 711.11}$$