To determine who spent more time writing per problem, we need to calculate the unit rate (minutes per problem) for each writer using the data provided.
Sonia's data:
Sonia spent 20 minutes per problem.
Maryna's data:
Maryna spent 25 minutes per problem.
Conclusion:
Maryna spent more time writing per problem at the unit rate of 25 min/problem.
The correct response is: Maryna spent more time writing per problem at the unit rate of 25 min/problem.