How to solve it?

4.35. a. By an algebraic or probabilistic argument, verify the following backward recursion formula of an n-year term insurance with a unit benefit: An = vq, - un+1 nP x 9xtn + UP x A,! x+ 1:n . b. Determine an appropriate starting value for use with this formula. c. Use your Illustrative Life Table with i = 0.06 to calculate the actuarial present value of a 10-year term insurance issued at ages x = 13, . . ., 130