Theory:

Complete the following table
 
S.No.
C.P.
S.P.
Profit
Loss
1
\(₹\)\(20\)
\(₹\)\(50\)
 
 
2
\(₹\)\(100\)
\(₹\)\(70\)
 
 
3
\(₹\)\(45\)
\(₹\)\(80\)
 
 
4
\(₹\)\(150\)
\(₹\)\(110\)
 
 
 
 
1. C.P. \(=\) \(₹\)\(20\)
 
S.P. \(=\) \(₹\)\(50\)
 
S.P. \(>\) C.P.
 
Therefore, there is a profit.
 
\(\text{Profit}\) \(=\) \(\text{S.P.}\) \(-\) \(\text{C.P.}\)
 
\(= 50 - 20\)
 
\(=\) \(₹\)\(30\)
 
  
2. C.P. \(=\) \(₹\)\(100\)
 
S.P. \(=\) \(₹\)\(70\)
 
C.P. \(>\) S.P.
 
Therefore, there is a loss.
 
\(\text{Loss}\) \(=\) \(\text{C.P.}\) \(-\) \(\text{S.P.}\)
 
\(=\) \(100 - 70\)
 
\(=\) \(₹\)\(30\)
 
 
3. C.P. \(=\) \(₹\)\(45\)
 
S.P. \(=\) \(₹\)\(80\)
 
S.P. \(>\) C.P.
 
Therefore, there is a profit.
 
\(\text{Profit}\) \(=\) \(\text{S.P.}\) \(-\) \(\text{C.P.}\)
 
\(= 80 - 45\)
 
\(=\) \(₹\)\(35\)
 
  
4. C.P. \(=\) \(₹\)\(150\)
 
S.P. \(=\) \(₹\)\(110\)
 
C.P. \(>\) S.P.
 
Therefore, there is a loss.
 
\(\text{Loss}\) \(=\) \(\text{C.P.}\) \(-\) \(\text{S.P.}\)
 
\(= 150 - 110\)
 
\(=\) \(₹\)\(40\)
 
 
Now, the table looks like this:
 
S.No.
C.P.
S.P.
Profit
Loss
1
\(₹\)\(20\)
\(₹\)\(50\)
\(₹\)\(30\)
Nil
2
\(₹\)\(100\)
\(₹\)\(70\)
Nil
\(₹\)\(30\)
3
\(₹\)\(45\)
\(₹\)\(80\)
\(₹\)\(35\)
Nil
4
\(₹\)\(150\)
\(₹\)\(110\)
Nil
\(₹\)\(40\)