Two months ago a bicycle shop was able to sold 120 bicycle. Then last month they were able to sold 138 bicycles already. Let’s find for the percentage that increases during those months. => 138 – 120 = 18 – thus, during those months, they added 18 bicycle as sold. => 120 is our 100% and 18 is our increased percentage => 18 / 120 = 0.15 * 100 = 15% Thus, it increases 15%, let’s check => 120 * .15 = 18.