Michael has $12,500 to invest. he invests part in an account which earns 4.2% annual interest and the rest in an account which earns 6.2% annual interest. he earns $669.50 in interest at the end of the year. how much was invested at each rate?
suppose he invest x dollars in one account, y in the other x+y=12,500 0.042x+0.062y=669.50 multiple the first equation by 0.042: 0.042x+0.042y=525 subtract this new equation from equation 2: 0.02y=144.50 y=7225 x=12500-7225=5275
