Haha, I don't think those answers belong to the question asked :P
The probability of rolling less than 3 is 2/6=1/3
So if you rolled 450 times you should expect to roll less than 3:
450(1/3)=150 times.
3. 5mn ( 2m + 6n + 1 )
4. 4a^3b^2c ( 18a^2b - 8c )
5. (X-15)(X+15)
6. -4(y-4.5)(y+4.5)
8. 2X(X-10)(X+10)
i am not sure if no. 8 is right
Y=1/2x +0. You add the 2x to the other side, and then divide everything by 4 to have only 1y.