10 points & ! show process : )

in a math class there are five equally weighted tests. a student has grades of
94, 92, 78, and 97 on the first four tests. to earn an a in the class, the students
must have an average of at least 90. what must the student get on the fifth test
to earn an a in the math class?

the student needs at least an 89 on the fifth test to earn an a in the math
class.