Theory:

Equation:
Any equation is a condition on a variable. It is satisfied only for a definite value of the variable.
Consider the following equation \(x - 3 = 10\).
 
Let us substitute a few values to \(x\).
 
Value
(\(x\))
Equation
(\(x - 3 = 10\))
Equation satisfied or not?
\(5\)
\(5\) \(-\) \(3\) \(=\) \(2\)
No
\(7\)
\(7\) \(-\) \(3\) \(=\) \(4\)
No
\(9\)
\(9\) \(-\) \(3\) \(=\) \(6\)
No
\(11\)
\(11\) \(-\) \(3\) \(=\) \(8\)
No
\(12\)
\(12\) \(-\) \(3\) \(=\) \(9\)
No
\(13\)
\(13\) \(-\) \(3\) \(=\) \(10\)
Yes
 
From the above tabular column, we can understand that the equation holds only to a specific condition.

Apart from \(13 - 3 = 10\), none of the conditions is satisfied.
An equation always contains an 'equal to' (\(=\)) sign in between.
It means that the left-hand side (LHS) is equal to the right-hand side (RHS).
 
In a valid equation, LHS will always be equal to the RHS.
Example:
1. \(2m + 8 = 25\)
 
2. \( k - 6 = 52\)
Expression without an 'equal to' (\(=\)) sign is not considered an equation.
Example:
1. \(b > 5\)
 
2. \(h\) \(×\) \(78\)