Substitution Method Calculator

Enter the six coefficients of a two-equation, two-unknown system and this solves it by substitution, showing each step as a line of working: which variable was isolated and why, the expression that replaced it in the other equation, the bracket multiplied out, the single-variable equation that falls out, the value taken back to the isolated form, and a check in both original equations. Answers stay exact, so a solution of 42/11 prints as a fraction rather than a rounded decimal, and decimal coefficients are cleared to whole numbers first. Parallel lines and repeated lines are named as no solution and infinitely many, with the line that says so.