Let the marked price of the article be M.
The selling price of the article after a discount of Rs 300 is M - 300.
After adding a 13% value added tax (VAT), the final selling price becomes:
(M - 300) + 0.13(M - 300) = 3051
Simplifying this equation, we get:
0.87M = 3051 + 300
0.87M = 3351
M = 3850
So the marked price of the article is Rs 3850.
The discount allowed on the marked price is (300/3850) × 100% = 7.79% (rounded to two decimal places).
Therefore, the discount percent allowed on the marked price of the article is 7.79%.