.
Let k be the number of correct answers, 0 <= k <= 10.
Then the number of wrong answers is 10-k.
The formula for the score as the function of "k" is
S(k) = 4k - (10-k) = 5k - 10.
So, when k = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, the values for S(k) are
-10, -5, 0, 5, 10, 15, 20, 25, 30, 35, 40 .
Thus, 11 different values of scores are possible.
Solved.