Using proportions, it is found that 8 more seventh graders are involved in the yearbook.
What is a proportion?
A proportion is a fraction of a total amount.
Researching the problem on the internet, it is found that 10% of the 6th graders and 18% of the 7th graders are on the yearbook, hence:
0.1 x 280 = 28 6th graders.
0.18 x 200 = 36 7th graders.
36 - 28 = 8
8 more seventh graders are involved in the yearbook.