A man bought $20$ litres of petrol. He used $12\frac{3}{4}$ litres of petrol in his car and $3\frac{2}{5}$ litres in his motor-bike. $k \mathrm{litres}$ petrol was left with him, find $k$.

Amita cut a cake into five equal pieces. She ate one piece. Her mother and father took one piece each. Her brother ate only half a piece. How much cake was left?

How many equivalent fractions can a fraction have?

You have learnt about proper, improper and mixed fractions. What kind of fraction is $0$ ?

You know how to convert an improper fraction into a mixed fraction. Now can you convert a proper fraction into a mixed fraction? Conversely, can you convert a mixed fraction into a proper fraction?