When chords intersect in a circle, the vertical angles formed intercept congruent arcs.

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

Can someone me out here number 4 plz

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%)