During the 1980s, sales of compact discs surpassed vinyl record sales. From 1985 to 1990, sales of compact discs in millions can be modeled by the formula f(x) = 51.6(x - 1985) + 9.1. whereas sales of vinyl LP records in millions can be modeled by g(x) = 31.9 (x - 1985) + 167.7. Approximate the year x when sales of LP records and compact discs were equal.