heather has divided $6300 between two invesments, one paying 9%, the other paying 4%. If the return on her investment is $372, how much does she have in each investment
assuming that the two investments are X & Y X + Y = 6300 X = 6300 - Y (1)
9/100X + 4/100 Y = 372 (2) replacing X from (1) into (2) 9/100(6300-Y) + 4/100 Y = 372 567 - 9/100Y +4/100Y = 372 (-9+4)/100Y = 372 - 567 5/100Y = -195 Y = 100*195/5 = 3900 From (1) we can get X X = 6300 - 3900 = 2400
