Total number of pages in the Java book = 450
Ratio in which the pages have been divided between core and advanced is = 7:2
Let us assume the common ratio to be = x
Then, the equation can be written as
7x + 2x = 450
9x = 450
x = 450/9
= 50
Then
The number of core pages in the Java book = 7 * 50
= 350
The number of advanced pages in the Java book = 2 * 50
= 100
So the book will have 350 core pages and 100 advanced pages.