Coi gia ban la 100%,gia von chiem so phan tram la:
100%-12%=88%
Gia von cua chiec dien thoai la:
4480000:100% x 88%=3942400(dong)
de lai 20% gia ban thi gia ban chiec dien thoai chiem so phan tram la:
100%+20%=120%
de lai 20% gia ban thi nguoi do phai ban chiec dien thoai voi gia:
3942400:100% x 120%=4730880(dong)
Dap so ban tu lam nhe ! good luck !