Answer:
Her grade must be an 89 or better
Step-by-step explanation:
to find the average you add all the numbers than divide but the total numbers of numbers so when she had the first two test her average was an 78.5 if she has an 85 it is close to the 80's but still less than but if she has a 90 she is averaged to be about 85 so if she gets an 89 she has an exact average of 82
