Answer:
He needs at least 77 on the 5th test.
T₅ ≥ 77
Step-by-step explanation:
If five numbers are to average 84, then their sum must be (5 x 84) = 420 .
Gale needs his five grades to add up to 420.
So far, he has (80 + 95 + 78 + 90) = 343 .
He needs at least (420 - 343) = 77 more points on the 5th test.