Translation:The doctor bought the car by check.
I see "a doctor" as a hint for γιατρός but not for ο γιατρός.
I've added "doctor" as a hint for γιατρός now, though.
o has a hint "the" which should be sufficient.
Please accept 'with check' and 'using check'—the word 'using' isn't in the Greek, but feels more natural than 'by check'.