How to Find the Tax in a Math Problem

This article describes how to solve math problems dealing with the price of an item, the tax that would be applied to it, and the total cost (price plus tax) of the item. The amount of tax (represented by "T" in our equations) on an item is the tax rate (represented by "R") multiplied by the price of an item (represented by "P"). The total cost of an item is the price of the item plus the amount of tax.

Instructions

Computing the Amount of Tax on an Item

1. Convert the tax rate percentage to a decimal. This is done by dividing a percentage by 100. For example, for a 6% tax, the tax rate "R" will be 6/100 = 0.06.

2. Multiply your tax rate by the price of the item to find the amount of tax. The equation for this is P*R=T. If your item's price "P" is $10.45 and the tax rate "R" is 0.06, the tax on the item is ($10.45)*(0.06) = $0.627.

3. Round your answer to the nearest cent. In our example, the amount of tax on our $10.45 item with a 6% tax would be $0.63.

How to Find the Total Cost of an Item

1. Convert your tax rate percentage to a decimal, as in section 1, to determine tax rate "R."

2. Add 1 to your tax rate. For example, we would add 1 to our rate of 0.06 to get a (1 + R) value of 1.06.

3. Multiply your (1 + R) value by the price of the item. For an item with a price "P" of $10.45. Our equation to find total cost "C" is P*(1+R) = C. In our example ($10.45)*(1.06 )= $11.077.

4. Round your answer to the nearest cent. In our example, the total cost of a $10.45 item with a 6% tax is $11.08.