After allowing a discount of 20% on the marked price of a lamp, a trader loses 10%. By what percentage is the marked price above the cost price?

Explanation

To solve the problem step by step, we can follow these steps:

### Step 1: Define Variables
Let:
- \( x \) = Marked Price (MP)
- \( y \) = Cost Price (CP)

### Step 2: Calculate Selling Price After Discount
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