Another way to substitute a variable by a value, besides with the | operator or the subst command, is with something akin to functional notation. You can follow an expression or expression name with equalities of the form variable=value.
Expr:=x+2*y+3*z |
then:
subst(Expr,[x=1,y=2]) |
or:
Expr | x=1, y=2 |
Expr(x=1,y=2) |
|
(h*k*t^2+h^3*t^3)(t=2) |
|