Suppose in Q1 it asks respondents for the number of cellphones in their household.
Q2 asks for the number of Nokia phones, the number of Motorola cell phones, and "other" cellphones.

Is there a way to ensure that respondents cannot continue the survey if Q2 does not sum to Q1?

Is there also a way to base Q3 on a condition where the number of Nokia phones is greater than the number of Motorola or other cellphones?

Thanks in advance.