Step 1: Calculate time taken for the first part of the journey

Using the formula $t = \frac{d}{v}$, the time taken for the first 230 km at 46 km/h is calculated as $t_1 = \frac{230}{46} = 5$ hours.

$t_1 = \frac{230}{46} = 5 \text{ hours}$

Step 2: Calculate time taken for the second part of the journey

Similarly, for the next 400 km at 100 km/h, the time taken is $t_2 = \frac{400}{100} = 4$ hours.

$t_2 = \frac{400}{100} = 4 \text{ hours}$

Step 3: Find total distance and total time

Sum both distances to get the total distance, and sum both times to get the total time spent traveling: $\text{Total Distance} = 230 + 400 = 630$ km and $\text{Total Time} = 5 + 4 = 9$ hours.

$\text{Total Distance} = 630 \text{ km}, \quad \text{Total Time} = 9 \text{ hours}$

Step 4: Compute average speed

Apply the average speed formula: $\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} = \frac{630}{9} = 70$ km/h.

$\text{Average Speed} = \frac{630}{9} = 70 \text{ km/h}$