### 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.

Apart from \(13 - 3 = 10\), none of the conditions is satisfied.

An equation always contains an 'equal to' (\(=\)) sign in between.

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**. \(h\) \(×\) \(78\)