Theory:

A solution of an equation is a number substituted for an unknown variable which makes the equality in the equation true.
Example:
Consider the equation \(x+3 = 2x-1\). Check whether \(x = 4\) is the solution of the equation.
 
Solution:
 
To verify whether \(x = 4\) is the solution of the equation, let us substitute \(x = 4\) in the given equation.
 
Let us substitute \(x = 4\) in LHS.
 
LHS \(=\) \(x+3\)
 
\(= 4+3\)
 
LHS \(= 7\)
 
Similarly, let us substitute \(x = 4\) in RHS.
 
RHS \(=\) \(2x-1\)
 
\(=\) \(2(4)-1\)
 
\(=\) \(8-1\)
 
RHS \(= 7\)
 
Since LHS \(=\) RHS, \(x = 4\) is the solution of the given equation.