Final answer:
To find out how much fuel is needed to travel 420 km when the car uses 1 litre of fuel to travel 12 km, we calculate 35 litres by setting up a proportion and solving for the unknown quantity.
Step-by-step explanation:
This is asking us to calculate how much fuel will be needed for a car to travel a certain distance, given its fuel consumption rate. To find the amount of fuel needed to travel 420 km when the car uses 1 litre of fuel to travel 12 km, we can set up a proportion. We know that 1 litre/12 km = x litres/420 km, where x is the amount of fuel needed for 420 km. To solve for x, multiply both sides of the equation by 420 km. This gives us: x = (420 km × 1 litre) / 12 km. By calculating, we find that x = 35 litres. Therefore, 35 litres of fuel will be needed to travel 420 km.