Two unknowns need two equations. Solving them finds the point where both conditions are true at once.

• Substitution: make one variable the subject, then substitute into the other equation.
• Elimination: add or subtract the equations to cancel one variable.
• Graphically, the solution is the point where the two lines intersect.
• Present the answer as a coordinate pair or clearly as x = …, y = ….

• Simultaneous — true at the same time.
• Intersection — the point common to both graphs.