Answer:
n = a + 99
Explanation:
Given that :
a = number of pages in algebra book 1
n = number of pages in geometry book
a = n - 99
The number, n of pages in a geometry book is ;
Pages in algebra book = (pages in geometry book - 99)
a = n - 99
a + 99 = n - 99 + 99
a + 99 = n