Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
a+b+c+d /. {a -> 3, b -> 4, c -> 5, d -> 6}
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random