Explain how you decided what number sentence to write for exercise 1 how to do that

He that is measured at 220° is a reflex angle. the opposite angle is obtuse. find the measure of obtuse .

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?