Undiscounted Shirt Price Calculation with Discount and Loss

Let the undiscounted price (original marked price) of the shirt be denoted by P.

Cost Price Calculation from Discount

The shirt was initially bought by the seller at a 10% discount. This means the seller's cost price (CP) was 90% of the undiscounted price (P): $CP = P \times (1 - 0.10) = 0.90P$

Selling Price to Cost Price Relation

The shirt was then sold to a friend at a 10% loss. The selling price (SP) is given as Rs. 729.00. The loss is calculated based on the cost price (CP). $SP = CP \times (1 - 0.10) = 0.90 \times CP$

Substitute the known SP:

$729 = 0.90 \times CP$

Solve for CP:

$CP = \frac{729}{0.90} = \frac{7290}{9} = 810$

The seller's cost price was Rs. 810.

Undiscounted Price Calculation

Now, we use the cost price (CP) found and the relationship from the initial purchase ($CP = 0.90P$):

$810 = 0.90P$

Solve for the undiscounted price (P):

$P = \frac{810}{0.90} = \frac{8100}{9} = 900$

The undiscounted price of the shirt was Rs. 900.