Answer: 54 , 55 , 56 , 57 , ...
Explanation:
Let the third grade be x , then Jacque scores in the three tests will be :
81 , 84 , x.
the average of the scores =

Since Jacque wants an average of at least 73 , this means that :





This means her possible scores will be :
54 , 55 , 56 , 57 , ...