So the first score is 7777.
The second score was 77 less than the third score.
So here we first want to find the total score, by multiplying 7474 by 3.
7474*3 = 22422
So the total test score was 22422.
So first subtract 7777 from 22422 to find the total score of the second and third exams.
22422 - 7777 = 14645
So the total test score of the two is 14645.
Now, since the second score was 77 less, there's a few ways to do it.
I'ma just do a random method.
Say the second score = x, and the third score = x+77.
x + x + 77 = 14645
2x = 14645 - 77
2x = 14568
/2 /2
x = 7284
So the second score was 7284.
The third is 77 more then that.
7284 + 77 = 7361
So her third exam score was 7361.