6. yes, it shows a function because you add one to X and it equals Y.
7. it has both
Http://www.jiskha.com/display.cgi?id=1412206557 here this should help
200
200*2 = 400
400*2 = 800
800*2 = 1600
1600*2= 3200
This is 5 numbers
If you want 5 numbers that are multiplies by 2
3200*2 =6400
A=8
Explanation: a+b=12 a-b=4
^^^^^^^ ^^^^^^
8+4=12 8-4=4
A=8