Acivic group is selling bumper stickers as a fundraiser. during the first week, they
sold 500 bumper stickers. during the second week, the group sold 50% more
bumper stickers than the first week. during the third week, the group sold 50%
fewer bumper stickers than the second week.
explain how you can use proportions to find the percent decrease from the first
week's sales to the third week's sales,

25%

Step-by-step explanation:

500 bumper stickers sold in the first week is 100%.  The bumper stickers sold in the second week is 50% more (150%).

500 / 100 = x / 150

x = 750

750 bumper stickers sold in the second week is 100%.  The bumper stickers sold in the third week is 50% less (50%).

750 / 100 = x / 50

x = 375

The bumper stickers sold in the third week as a percentage of the bumper stickers sold in the first week is:

375 / 500 = x / 100

x = 75

The bumper stickers sold in the third week is 75% of the bumper stickers sold in the first week, which means there was a 25% decrease.