Please show all work. Thank you.

They decide to shop for the new house. They choose items that amount to $1,600.00. The store has 2 options for purchasing: I. Financing at 6.4% simple interest per year for 2 years with a 20% down payment. II. No down payment and financing at 6.5% simple interest for 3 years. Answer each of the following questions separately, showing all your work to reach each answer. Which option should they choose if they want the smallest interest charge? Show all steps to support your answer. Which option should they choose if they want the smallest monthly payment? Show all steps to support your answer If they decide to defer any purchases and invest the $1600 at 2.5% per year simple interest, how long will it take to earn $250 interest