Trevor is a comic book illustrator. In the past three months, he has drawn 220 pages of the comic. The comic he illustrates releases a new issue once a month. The first and second months' issues were the same number of pages, but the third month's issue was four pages longer than either of the others. How many pages was the first issue of the comic? Let's be accurate as possible.
Let P be the number of pages of the first issue of the comic. The second issue is the same number of pages, so the first and second issues are P + P = 2P pages. The third issue is 4 pages longer, so it is P + 4 pages. All three issues are 2P + P + 4 = 3P + 4 = 220 pages long. Thus, 3P = 220 - 4 = 216 pages. Therefore, the first issue of the comic was P = 216 / 3 = 72 pages.
The answer: 72.