8
It might be possible to work this in your head. Your 98 is 100 minus 2. This means 98 plus 98 is 100 plus 100 minus 2 minus 2. That's 200 minus 4 which gives 196 as the answer.
106
98 - 69 = 29
It is the same as: 7,000,000 minus 5,300,000 = 1,700,000
8n + 7 - n - 98 = 7n - 91
15 - 98 = -83
53
106
106
Negitive 100
The GCF is 2.
2010 - 1912 = 98