Mrs Hamilton's commision
175000 x 0.04 (4%) = 7000
Mrs Hamilton received 4725
7000 x 0.01 = 70 (1%)
4725 / 70 = 67.5%
She received 67.5% of her total commission
David's Computer = C
Working
1080 x 0.8 (80%) =864
864 x 1.08 (108%) = 933.12
The computer cost $933.12 dollars
Suzanne's sweater = B
$40 / 100 = 0.4 (1%)
40 - 25 = 15 (difference)
15 / 0.4 = 37.5%
Suzanne received a discount of 37.5%