Simple, what you're basically doing is simplifying,

well, you have 3x and you have

12/3=4
and you can "cancel" out an x, making your answer,

.
Hdhhdhzhzhzj on da guys you welcome
9) 0.31
10) (7x10^6)-(3x10^3)
7000000-3000=6997000
6.997x10^6
Hope this helps :)
3/4 I believe since 6 1/4- 51/2 is 3/4