Among the trips in August 2013, how many bikes were borrowed from Redwood City.
Redwood City is the name of the city; trips in August 2013 refers to start_date like '8%2013%';
SELECT COUNT(T2.start_date) FROM station AS T1 INNER JOIN trip AS T2 ON T2.start_station_name = T1.name WHERE T2.start_date LIKE '8/%/2013%' AND T1.city = 'Redwood City'