What is the sum of a geometric series Sn=a+ar+ar2+ar3+…+arn-2+arn-1?

The highest common factor of 132 and 220

Set up and solve a proportion for the following application problem. if 55 pounds of grass seed cover 404 square feet, how many pounds are needed for 7272 square feet?

Awoman has 14 different shirts: 10 white shirts and 4 red shirts. if she randomly chooses 2 shirts to take with her on vacation, then what is the probability that she will choose two white shirts? show your answer in fraction and percent, round to the nearest whole percent.