Can you please answer this thank you

Which is a true statement about an exterior angle of a triangle a. it is formed by two segments that are not sides of the triangle, b. it forms a linear pair with one of the interior angles of the triangle, c. it is complementary to one of the interior angles of the triangle. d. it is formed by two segments that are sides of the triangle.

What is the probably of getting heads when poing a coin and getting a number greater than or equal to 5 when rolling a single diea) 1/6b) 1/3c) 1/4d) 1/12

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18