Amanda invested a total of $2,200 into three separate accounts that pay 6 %, 8 % , and 9 % annual interest. Amanda has three times as much invested in the account that pays 9% as she does in the account that pays 6%. If the total interest for the year is $178, how much did Amanda invest at each rate? Use the variables x = amount invested at 6%. y amount invested at 8%, z amount invested at 9% a. Write an equation for the total amount invested. b. Write an equation for the total interest earned for the year. (Use simple interest for 1 year, IPrt.) c. Write an equation representing the statement, "Amanda has three times as much invested in the account that pays 9% as she does in the account that pays 6%