Find the distance between the point (1,4) and (-6,-1)

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.

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

Which best explains why this triangle is or is not a right triangle ?