Feed it two or three linear equations and watch elimination, substitution or Cramer's rule unwind line by line in exact fractions — never rounded decimals. Parallel and identical lines get diagnosed as no-solution or infinitely-many families, with the free-parameter form written out.
Substitution is offered for 2×2 systems only; Cramer works on both sizes and prints every determinant. Decimals are exact here — 8.4 is stored as 42/5 before any working starts.