Let [tex]n[/tex] be the total number of stickers. If she puts 21 stickers on a page, she will fill up [tex]p[/tex] pages such that
[tex]n = 21p + 14[/tex]
Suzanna has between 90 and 100 stickers, so
[tex]90 \le n \le 100 \implies 76 \le n - 14 \le 86[/tex]
[tex]n-14[/tex] is a multiple of 21, and 4•21 = 84 is the only multiple of 21 in this range. So she uses up [tex]p=4[/tex] pages and
[tex]n-14 = 4\cdot21 \implies n = 4\cdot21 + 14 = \boxed{98}[/tex]
stickers.
