Find the values of x, y, and z in the diagram below. interior and exterior angles of triangles!
320
740
X =74
y =
z =
2009
X
у

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%)