How many Grand Prix were the winning constructor Benetton - Ford and the pole position was Michael Schumacher?
create table table_1137702_3 (grand_prix varchar, winning_constructor varchar, pole_position varchar, PRIMARY KEY (grand_prix))
select count(grand_prix) from table_1137702_3 where winning_constructor = "benetton - ford" and pole_position = "michael schumacher"