Evelyn read 25 pages of a book on friday morning. she read 1/4 of the remainder on friday afternoon if she still had 90 pages to read after friday afternoon .how many pages were in the book

145 pages.

25 + 1/4 x (X - 25) + 90 = X

100 + X - 25 + 360 = 4X

435 + X = 4X

435 = 3X

X = 145

Ok so we are calling the total number of pages in the book X. Friday morning, they read 25 pages. Friday afternoon, they read 1/4 of what is left. Since they already read 25 pages, we can say that the remainder of the pages is the total, X, minus 25, giving us the amount of pages read on Friday afternoon 1/4 (X - 25). They then say that the rest of the pages in the book after Friday is 90. Therefore what they read of friday plus 90 is the total amount of pages in the book. After this point, it is simple algebraic solving in order to find X. If you plug 145 in for the total amount of pages, you will see that it works.

What do you mean by that?

1.17+3.99a. you combine the terms with a to create 3.99 and the 1.17 stays because it has no like terms or a variable