If the selling price of a laptop, including VAT, is 576 euro, find the price of the laptop before VAT is added on.

It depends on what the VAT rate is. Let's call the VAT rate V. Then for an item priced at P the VAT is P times V, and the total amount you have to pay is:

Total = P x (1 + V).

For this problem you know the total is 576, so if you know the rate V you can solve for P.