She purchased 5 paperbacks at $4 and 3 hardbacks at $8 for a total of $44.
h = number of hardback books p = number of paperback books h + p = 8 so h = 8-p . 4*p = price of paperbacks 8*h = price of hardbacks 4*p + 8*h = 44 . substitute h = 8-p . 4p + 8(8-p) = 44 4p +64 -8p = 44 -4p = -20 p = 5 h = 8-p h = 3 . check to be sure the values are right 4*5 = 20 3*8 = 24 20 +24 = 44
