Provide your best answer for the following math problem. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The problem is: a teacher grades students ’ tests by subtracting twice the number of incorrect responses from the number of correct responses . if student b answers each of the 100 questions on her test and receives a score of 73 , how many questions did student b answer correctly ?
91
37.5 <This is incorrect, the answer should be a whole number.>