Answer:
Sandra's final score is
.
Step-by-step explanation:
It is provided that each question Sandra answers incorrectly changes her overall score by -3/4 points.
That is, for every incorrect answer Sandra looses 3/4 points.
At a moment Sandra's overall score was
points.
And then she answered the last questions incorrectly.
Compute the final score as follows:
Final score = Sandra's overall score - 

Thus, Sandra's final score is
.