Need some help with my Algebra, not good at word problems...?

In 1990, the life expectancy of males of a certain country was 63.7 years. In 1997, it was 66.8 years. Let E represent the life expectancy in year t and let t represent the number of years since 1990. I'm just not good at this and don't understand how to do this problem, any help would be appreciated.