Answer:
x= (y+40)-(y-330)
Step-by-step explanation:
According to the information provided, the difference in their scores would be the result of subtracting Austin's SAT score from Alexandra's SAT score.
Then, as Alexandra's SAT score was 40 points above the average score this means that you have to add 40 to the average score to get her result. Also, as Austin's SAT score was 330 points below the average score, this means that you have to subtract 330 from the average score. With this you can write the expression:
x= difference in their scores
y= average score
x= (y+40)-(y-330)
Each medal is different and is handed out depending on the outcome of the race/order of the racers, so we're counting the number of permutations. 4 medals are given to 4 runners, so there are

possible ways to do it.
Number 7 is C because all of them are less than 1/2 or 0.50