Let's assign variables for the unknowns. Let x be the amount of total sales while x is the amount of net sales. It is called net sales because a percentage is still deducted from it. The equation will be written as:
Net Sale = Total Sales - 0.25*Total Sales
y = x - 0.25x
y = 0.75x
The answer is 3 because all you have to do is plug in the answer and then you have to solve the answer and go from there.