In 1990 an egg cost 2c less than in 1991. In 1992 an egg cost 4c more than in 1991. The cost of 11 eggs in 1990 was the same as the cost of 8 eggs in 1992. Find the cost of an egg in 1991. (Hint: let the 1991 cost of an egg be n cents. Express the 1990 and 1992 costs in terms of n)