Basically, I use Wolfram but it tediously makes me change all the variable names to simple letters.

For example if I make a variable called “pixelsize”, wolfram doesn't understand what I am trying to do, and I have to just change it to “a”. This gets very tedious to do.

I am looking for a good calculator that is the same as wolfram, but doesn't have that limitation. Wolfram fulfills all my needs, except the last thing I tried to get it to solve it ran out of computation time. And asked me to upgrade to Pro for more computation time. I might consider upgrading to Pro, except that I don't like how it doesn't understand variable names. I might upgrade to pro anyway if nobody can find a good online calculator.

@taby Yep that is the best one I found so far. It solved every equation I put in it so far except the one I need. Maybe it is not the calculator's fault but maybe I made an error (not in my code, but in my math theory.)

There is also EES but they are expensive.