To solve this, let's break it down step by step:

1. Fuel consumption per 100 km: The car uses 9 liters of petrol for every 100 km.
2. Distance to drive: The total distance is 1500 km.
3. Tank capacity: The tank holds 68 liters of fuel.

Step 1: Calculate total fuel required for 1500 km

To find out how much fuel you'll need to cover 1500 km, we can use the car's fuel consumption rate.

$\text{Fuel needed} = \left(\frac{1500 \, \text{km}}{100 \, \text{km}}\right) \times 9 \, \text{liters} = 15 \times 9 = 135 \, \text{liters}$

Step 2: Calculate how many tanks of fuel are needed

Since the car's tank holds 68 liters, we can now find how many full tanks are required to provide 135 liters of fuel.

$\text{Number of tanks} = \frac{135 \, \text{liters}}{68 \, \text{liters per tank}} = 1.985 \, \text{tanks}$

Thus, you would need approximately 2 full tanks to cover 1500 km.

Do you want further details on any steps or more clarifications?

Here are 5 related questions to expand your understanding:

1. How would the number of tanks change if your car's fuel efficiency improved?
2. How far could you drive with just one tank of fuel?
3. What if you drove only 1000 km? How many tanks would that take?
4. How would varying road conditions affect your fuel consumption rate?
5. How much would it cost to fill 2 tanks of petrol at your current fuel price?

Tip: Maintaining your car's tire pressure and reducing excess weight can improve fuel efficiency.