I'm trying to make a program, and at the end of the code, I check which variables are missing to be calculated and solve them through a system ... to do this, I keep the list of unused variables in another variable, but texas Does not accept such action.
In the following image I gave an example of the problem!
![Image](https://image.ibb.co/crxuO5/problem_ti_nspire.png)
Is there any way to resolve this?
Thank you all.