Janice bought three lamps for her new apartment in a city where the sales tax rate is 5%. The lamps cost $25, $35, and $45. Find the total cost of her lamp purchase, including sales tax.

Remark

You could do this by taking 5% of each lamp as

5% * 25 + 25

5% * 35 + 35

5%*45 + 45

The easier way is to pretend that she bought all three at the same place at the same time.

(25 + 35 + 45) * (5/100) + 105

Easier yet is to do it this way.

(35 + 25 + 45) * 1.05 = 105 * 1.05 = 110.25