Table: mex_grand_prix_1969
Columns: driver
constructor
laps
time_retired
grid

Question: What is the average grid for piers courage?
SQL: SELECT AVG("grid") FROM mex_grand_prix_1969 WHERE "driver" = 'piers courage'

Question: Who drove 53 laps?
SQL: SELECT "driver" FROM mex_grand_prix_1969 WHERE "laps" = 53

Question: What is the lap total for george eaton, with a grid under 17 retiring due to gearbox?
SQL: SELECT SUM("laps") FROM mex_grand_prix_1969 WHERE "time_retired" = 'gearbox' AND "driver" = 'george eaton' AND "grid" < 17

Question: How many laps for denny hulme with under 4 on the grid?
SQL: SELECT SUM("laps") FROM mex_grand_prix_1969 WHERE "driver" = 'denny hulme' AND "grid" < 4