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( i ) How many kilometres will it go in 20 litres of petrol ?

( ii ) How much petrol is required to cover a distance of 261 km?

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Now, in question the only information which is provided is that A car is covering a distance of 145 km in 10 litres of petrol. And we have to find how many kilometres a car will go in 20 litres of petrol and also how much petrol is required to cover a distance of 261 km.

Now, let us first find how many kilometres does a car cover in 1 litre of petrol.

Here, the car covers 145 kilometres of distance in 10 litres.

So, in 10 litres = 145 km distance covered.

So, distance covered by a car in 1 litre of petrol will be equals to

1 litre $=\dfrac{145}{10}$ km

$\dfrac{145}{10}=14.5$km

That is, in one litre of petrol a car travels a total distance of 14.5 km.

Now, we have to find how many kilometres a car travels in 20 litres of petrol.

So, we have 1 litre $=\dfrac{145}{10}$ km

Then, in 20 litre of petrol, we have

\[20~\times 1\text{ }litre\] $=\dfrac{145}{10}\times 20$ km

On Simplifying, we get

$\dfrac{145}{10}\times 20=145\times 2km=\text{ }290\text{ }km.$

Hence in 20 litres of petrol a car travels a total distance of 290 km.

Now, we have to find that, to cover 261 kilometres how much litres of petrol do cars need.

If, we have 1 litre $=\dfrac{145}{10}$ km, then

We can re - write it as $\dfrac{10}{145}litres=1km$ which means t cover 1 kilometre of distance, we need $\dfrac{10}{145}litres$ of petrol.

So, for 261 km of distance petrol needed will be equals to

$261\times 1km=261\times \dfrac{10}{145}litres$

On simplifying, we get

$261km=\dfrac{2610}{145}litres$

Dividing 2610 by 145, we get

$261km=18litres$