Ithink of a number i add 16 subtract 30 and my answer is 36 what was my number

Three coins are flipped. what is the probability that there will be at least two tails?

Plz ( true - false) all triangles have interior angles whose measure sum to 90.

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%)