Jada has earned a total of 400 points so far.
141 + 87 + 81 + 91 = 400
There are a total of 450 points possible so far.
150 + 100 + 100 + 100 = 450
Jada has 400/450 or about 88.89% of the possible points, so no, she does not have 90%.
Adding in a 100-point test, the total number of points would become 550 and 90% of 550 is 495 points.
0.90 x 550 = 495
To finish the class with an A, Jada needs to have 495 points. She currently has 400 points. This means she needs a 95 on the final to finish the class with an A.