Assume Cost Price

Let the cost price of the goods be $100$.

$CP = 100$

Calculate Selling Price

Since the shopkeeper makes a gain of $8\%$, the selling price ($SP$) is $108$ units.

$SP = 100 + 8 = 108$

Determine Marked Price

A $10\%$ discount is allowed on the marked price ($MP$), meaning $SP = 0.9 \times MP$. Solving for $MP$ gives $\frac{108}{0.9}$.

$MP = 120$

Calculate Markup Percentage

The percentage above the cost price is $\frac{120 - 100}{100} \times 100\%$, which yields $20\%$.

$\text{Markup}\% = 20\%*$