Listing above cost and allowing a cash discount: A trader lists articles 20% above cost and allows a discount of 10% at sale. What is his overall gain percentage?

Introduction / Context:
Mark-up followed by discount produces a net selling price that is the product of the two factors. Compare this net selling price with cost to find the profit percentage. This is a staple computation for successive mark-ups/downs.

Given Data / Assumptions:

• Cost = C.
• List price M = 1.20C.
• Discount = 10% ⇒ S = 0.90M.

Concept / Approach:
Net selling price S = 0.90 * 1.20 * C = 1.08C. Gain% = (S − C)/C * 100 = (1.08 − 1) * 100 = 8%.

Step-by-Step Solution:

Verification / Alternative check:
Assume C = 100 → M = 120 → S = 108 → profit = 8, i.e., 8%.

Why Other Options Are Wrong:
5%, 6%, 10%, 12% do not match the exact factor product 1.08.

Common Pitfalls:
Adding 20% − 10% = 10% incorrectly; successive changes must be multiplied.

Final Answer:
8 %