One single discount which is equivalent to 20%, 10% and 5% is given by:
Explanation:
Let's say the initial vaue is 100.
Value after 20% discount = 100 - 20 = 80
Value after 10% discount = 80 - 8 = 72
Value after 5% discount = 72 - 3.6 = 68.4
∴ Total discount = 100 - 68.4 = 31.6
∴ Discount % = 31.6%
Hence, option (b).