At the beginning of the year, John had $40 in savings and saved an additional $13 each week thereafter. Isaac started the year with $80 and saved $9 every week. Let J represent the amount of money John has saved tt weeks after the beginning of the year and let I represent the amount of money Isaac has saved t weeks after the beginning of the year. Write an equation for each situation, in terms of t, and determine the number of weeks after the beginning of the year until John and Isaac have the same amount of money saved.