A blogger who is just starting out made three videos. So far, she has 312 subscribers, who watched one, two, or all three videos
. The three videos got 740 total views all together. Assuming each subscriber only viewed a particular video once, how many more people watched all three videos than only one video?
116. Suppose x subscribers watched only one video, y watched two, and (312-x-y) watched three. There are 740 views in total, so x+2y+3(312-x-y)=740. -2x-y=-196, or 2x+y=196. The number of people who watched three videos is 312-x-y=312-(2x+y)+x=312-196+x=116+x. 116+x-x=116.
