[R] is how much less than the total number of masks sold on Wednesday?

Total number of masks sold on Monday = 432/0.72 = 600 Number of N95 masks sold on Monday = (600 – 60)/2 = 270 Number of surgical masks sold on Monday [P] = (600 – 270) = 330 Total number of masks sold on Tuesday = 432 Number of surgical masks sold on Tuesday [Q] = (80/100) × 330 = 264 Number of N95 masks sold on Tuesday [R] = 432 – 264 = 168 Total number of masks sold on Wednesday = (600/60) × 43 = 430 Number of surgical masks sold on Wednesday = (20/43) × 43 = 200 Number of N95 masks sold on Wednesday [S] = 430 - 200 = 230 Required difference = 430 – 168 = 262