If a pair of linear equations is consistent, then the lines will be

Condition for a consistent pair of linear equations -

Consistent equations means the equations must have solution so lines may either coincide(with infinitely many solutions) or with a unique solution {lines must not be parallel}.

1) Must not be parallel so,

a1/a2 b1/b2 [intersecting lines with unique solution]

2) Also the lines can coincide, so,

a1/a2 = b1/b2 = c1/c2 [coincident or dependent]