Angle 2 and angle 3 equal 180 due to the what axiom

An alternative to car buying is to make monthly payments for a period of time, and then return the vehicle to the dealer, or purchase it. this is called

(01.04 lc)multiply 1 over 6 multiplied by negative 1 over 2. negative 1 over 3 negative 1 over 12 1 over 12 1 over 3

Which of the following is missing in the explicit formula for the compound interest geometric sequence below?