HELP ME ASAP. When are supplementary angles congruent?

always
if they are right angles
if they are acute angles
never

Given a: b and b: c, find a: b: c. write the ratio in simplest form. a: b=6: 10 and b: c=21: 33

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

Sam is picking fruit from a basket that contains many different kinds of fruit. which set of events is independent?