Validating a response based on previous questions

Hi, I am a new joiner and I am not familiar with the XLScode, I am still a beginner, would like to ask:
I want to add 2 data from previous questions.
1st questions (grown): How many crops that grown? let say 50 trees
2nd questions (additional): How many additional crops tha t been planted? 50 trees

so in the 3rd questions: How many crops that been blooming?
I would like to have a validation, where in total, based on the example is more than or equal to 0 (zero) and less than or equal to 100.
how should I write on the validation criteria validation code?
I tried to write .<0 and.<=(${grown}+${additional}) but seems it didn’t work. Pls kindly help

Welcome to the community @horekultura! You could do the same as outlined in the image shared below:

In the survey tab of your xlsform:

Data entry screen as seen in Enekto: (when a wrong entry is made)

Data entry screen as seen in Enekto: (when a correct entry is made)

Reference xlsform:

Constraint.xlsx (9.0 KB)