What is the total billed cost for each vendor after discounts and allowances (assume the invoices ...

(Bella Notte and Je Veux offer the lowest cost of merchandise)
Bella Notte:
Dress Pumps - 73.1, Wedges - 38.9, Ballet Flats - 37.8, Slides - 43.2, Total before discounts - 193.0
Dress Pumps - 145, wedges - 135, Ballet Flats - 105, Slides - 120 = Total before discounts - 505

193.0 x 3 = 5.8
193.0 x 5 - 9.7
193.0  5.8  9.7 = 177.5

If using the direct method  work should be shown this way:

193 x 3 = 5.79
193 - 5.79 = 187.21
187.21 X 5 = 9.36
187.21  9.36 = 177.85

505 X .97 = 489.85
489.85 X .95 = 465.36

Je Veux:
Dress Pumps - 74.6, Wedges - 40.3, Ballet Flats - 39.6, Slides - 45.0, Total before discounts - 199.5

199.5 x 5 = 10.0
199.5 x 2 = 4.0
199.5 - 10.0 - 4.0 = 185.5

Serge:
Dress Pumps - 75.6, Wedges - 40.3, Ballet Flats - 41.4, Slides - 43.2, Total before discounts - 200.5

200.5 x 3 = 6.0
200.5 x 2 = 4.0
200.5 - 6.0 - 4.0 = 193.5

Rouge:
Dress Pumps - 78.1, Wedges - 41.8, Ballet Flats - 42.8, Slides - 46.8, Total before discounts - 209.5

209.5 x 2 = 4.2
209.5 x 5 = 10.5
209.5 - 4.2 - 10.5 = 194.8