Maybe this approach does what you want ... > QQ := a*t^2+b = c/d; 2 QQ := a t + b = c/d > solve( subs( a=1.0, t=3, b=4, d=7, QQ ), c ); 91 > printf( " %s %g", "c = ", solve( subs( a=1.0, t=3, b=4, d=7, QQ ), c ) ); c = 91 > plot( solve( subs( a=1, c=4, d=7, QQ ) ,b), t=0..10, axes=boxed, labels=["t","b"], title="Equation QQ" ); <<< plot output will appear here >>>