A fully discrete whole life policy with quarterly premiums is issued to a life age x on August 1. The benefit reserve on the December 31 following the t-th policy anniversary is calculated as

(a)(_tV_x⁽⁴⁾) + (b) (_t+1V_x⁽⁴⁾) + (c)(P_x⁽⁴⁾)

Determine a, b, and c