So I'm currently implementing a physics task for a course and, in a way, struggle with the PRT.
The students are supposed to substitute one equation into another (conservation of energy and momentum) and then enter some values. This might be going too far, but I want to continue checking their answers even if they didn't substitute correctly. My problem, that I unfortunately couldn't resolve by now, is that I cannot tell, which of two variables (v1 and v2) they eliminated during the substitution. However, checking the calculated values requires me to do so, since I am not aware of a way to solve the equation they entered for either v1 or v2, depending on which one has been eliminated in the preceeding process.
Any help would be highly appreciated, thanks in advance!