also one more question , from which book this question taken?

d Mike a used automobile for $3000. Mike paid $500 as a down payment and at three personal notes for the remainder due. The principal of each note was 00, $750, and $750. The $1000 note was due 1 year after the purchase, the second note was due 2 years after the purchase, and the third note was due 3 years anter the purchase. The annual simple interest agreed to by Pat and Mike was 10% for the first note, 12% for the second note, and 15% for the third note. How much total interest was paid to Pat by Mike? (2.3)