Hold n and one variable constant, drag the independent variable, and watch the dependent one respond. n = 1.00 mol, R = 0.08206 L·atm·mol⁻¹·K⁻¹.
Try: select Boyle and shrink the volume — pressure climbs along the curved hyperbola (P ∝ 1/V). Switch to Charles: the V-vs-T line aims straight at the origin at 0 K (absolute zero).