This is a bit more of a general question.

I am having students enter the equation of a line (a regression line). Since rounding and different versions of a calculator can give slightly different versions, I give the students an error tolerance. I then have the students answer some subsequent questions using the line. (For instance, plug a value in or set equal to a value and solve.) Unfortunately, even a small error tolerance in the original equation they enter can yield a rather large error threshold later in the problem. It would be much better to base the answer off of the student's input, creating an error threshold that is smaller but dependent on their entered answers.

Is it possible to read in the student's answer as a function so as to pull out the values?

For instance:

The student enters mx+b.

I set $student_slope = m, $student_intercept=b (possibly as $student_intercept = $student_ans(0))

I ask them to solve for when the line equals c, so I set the answer as ans = (c-student_intercet)/(student_slope).

I can then use the cmp method to calculate and specify the error tolerance I want for their answer.

This is similar to the discussion on using $inputs_ref and $multians, but I am looking for something hopefully simpler. I particularly want to avoid having two boxes where they enter the slope in one box and the intercept in the other (though I may do this in the future).

Thank you