According to data from the U.S. Department of Defense and Congressional Research Service, the estimated annual cost y (in thousands of dollars) per active duty service member in the U.S. Armed Forces in year x is given by the equation:

6,000x – 2,000y + 136,000 = 0 (4< x < 18) where x=4 corresponds to 1994. Find the year in which the estimated annual cost per service member is (a) $92,000 (b) 110,000.