35,000,000 what is the order of magnitude of this number

Simplify (a/b - b/a) times (a - a^2/a+b) a - a^2/a=b is a mixed number

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a

1. evaluate 8x(2)y9(-2) for x=-1 and y=2 2. simplify the equation. -() 3. simplify the expression. [tex]\frac{5}{x(-2) y9(5)}[/tex]