Iam a number between 60 and 100 my ones digit is two less than the digit in my ten. i'm a prime number what is my number?

What is the approximate circumference of the circle shown below?

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?

Given the diagram below, michael writes, "segment ac is congruent to segment ac." which of the following reasons allow him to write this statement?