Substitute and evaluate
Hello, I would like to ask a really easy question:
How can I substitute a variable into an equation and have it evaluated simultaneously? If I have $f = a + b$ and would it to return $5$ if $a=2$ and $b=3$, how shall I proceed?
I've tried the following
a, b = var('a, b'); f = a + b; a = 2; b = 3; f
But it returned
a+b, which is not what I had in mind. Thanks for the help in advance!