Step-by-step explanation:
100% = 20
20% = 100% × 20/100 = 100%/5 = 20/5 = 4
so, sale price is then 20 - 4 = 16
100% = 60
10% = 100% × 10/100 = 100%/10 = 60/10 = 6
so, sale price is 60 - 6 = 54
100% = 50
30% = 100% × 30/100 = 100% × 3/10 = 50×3/10 = 15
so, sale price is 60 - 15 = 45