+328 Linda drove 50 miles from San Jose to San Francisco in 90 minutes. For the first 30minutes, without much traffic, her average speed was 60 miles an hour. In the second 30 minutes, due to a traffic accident along US 101, her average speed dropped to 35miles an hour. She was stuck in traffic for the last 30 minutes near San Francisco.What was her average speed, in miles per hour, during the last 30 minutes?
