Andy and sam are saving money to go on their senior trip. the amount of money that andy will have at the end of each week, w, can be expressed at a(w) = 20w + 300. the amount of money that sam will have at the end of each week, w, can be expressed at s(w) = 15w + 400. they have decided to combine their savings accounts. write a function that expresses the total amount, t(w) they have in their savings account at the end of each week.