Given that,
A car uses a litre of petrol to travel 4 km.
To find,
How many litres will it use to travel 32 kilometres.
Solution,
We have,
1 litre = 4 km
or
1 km = (1/4) litre
Let it will use x litres to travel 32 km.
32 km = (32/4) litres
= 8 litres
Hence, 8 litres it will use to travel 32 km.
What do you not understand
Let's apply the formula giving the slope:
m=(y2-y1) /(x2-x1) , let's plug:
m= (8-0) / (3-(-1)) ====> m= 2
It requires a circular movement to either left or right to get the figure on the right side of the paper.