Respuesta :

he bought 200 of them
200*2.80=$560
marked up 90%
90% of 560=0.9*560=504
560+504=1064
he sold all 200 for a total of 1064, or an average price of $5.32 each
2.8*1.9= 2.8 + 2.8*.90= 5.32