When calculating this, you should proceed in the following way:
if 7/12 of the magazine are articles and it has 204 pages, then the first fraction can be used to calculate how many of these pages are represented by articles, we do this by multiplying both numbers:
(7*204)/12 =
(7*204) = 1428
1428/12 = 119
119 is the number of articles.
To get the number of adverts, simply 204 - 119 = 85
There are 85 pages with adverts.
