Let P be the number of pages in the first chapter.
The second chapter has P + 3 pages.
The third chapter has P + 3 + 3 = P + <<+3+3=6>>6 pages.
The fourth chapter has P + 6 + 3 = P + <<+6+3=9>>9 pages.
The fifth chapter has P + 9 + 3 = P + <<+9+3=12>>12 pages.
The whole book has P + 3 + P + 6 + P + 9 + P + 12 = 5P + 30 = 95 pages.
Thus, without the 30 extra pages from additional chapters, 5P = 95 - 30 = 65 pages.
Therefore, the first chapter had P = 65 / 5 = <<65/5=13>>13 pages.
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