Decimal: (could be used when using a ruler to count millimeters). Fraction: (could be used when calculating an equation with ordinary fractions). Percentage: (could be used in chemistry to calculate upon admixtures).
You take the price with tax and subtract the tax (by 0.??), and that'll give you your answer. In this case, you the starting price of $14.55 and subtact 0.6 (6%), which gives you $13.95.