Table: us_rapid_transit_2012
Columns: annual_ridership_2012
rider_per_mile
opened
stations
lines

Question: What is the number of annual ridership with a station that has more than 13 stations and larger than 4 lines?
SQL: SELECT SUM("annual_ridership_2012") FROM us_rapid_transit_2012 WHERE "stations" = 13 AND "lines" > 4

Question: How many lines have fewer than 44 stations and fewer than 881 riders per mile?
SQL: SELECT COUNT("lines") FROM us_rapid_transit_2012 WHERE "stations" < 44 AND "rider_per_mile" < 881