Theory:

1. A notebook is bought for \(₹\)\(25\) and sold for \(₹\)\(40\). Find the profit or loss.
  
C.P. of the notebook \(=\) \(₹\)\(25\)
 
S.P. of the notebook \(=\) \(₹\)\(40\)
 
S.P. \(>\) C.P.
 
So, there is a profit.
 
\(\text{Profit}\) \(=\) \(\text{S.P.}\) \(-\) \(\text{C.P.}\)
 
\(= 40 - 25\)
 
\(=\) \(₹\)\(25\)
 
  
2. If \(1\) \(kg\) of sugar is bought for \(Rs.90\) and it is sold for \(Rs.67\). Find the profit or loss.
  
C.P. of \(1\) \(kg\) of sugar \(= Rs.90\)
 
S.P. of \(1\) \(kg\) of sugar \(= Rs.67\)
 
In this case, C.P. \(>\) S.P.
 
Therefore, there is a loss.
 
\(\text{Loss}\) \(=\) \(\text{C.P.}\) \(-\) \(\text{S.P.}\)
 
\(= 90 - 67\)
 
\(= Rs.23\)
 
  
3. If a box of chocolates is bought for \(Rs.120\) and it is sold for \(Rs.120\). Find the profit or loss.
 
In this case, C.P. \(=\) S.P.
 
Therefore, there is no profit or loss.