A) Which two of these expressions are equivalent to 3 * a?
A) 3°
B) a + a + a
C) За
D) a
b)
Which two of these expressions are equivalent to a 2?
A) 2a
B) 1/2 a
C) 2/a
D) a/2

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)