ana maría had 28,000 dollars to invest. she divided the money into three different accounts. at the end of the year, she earned $1.160 in interest. the annual yield on each of the three accounts was 3.5%, 4.25%, and 4.75%. the amount of money in the 4.75% account was 75% of the amount of money in the 3.5% account. define the variables and write a system of equations to represent the situation.