By adding all the numbers and dividing by 7 ( the amount of numbers) you know that the answer will be about 166.3
I don't really get this question but simply put, if you are in college syntax matters very much. (13-4) = 9 *(x-5) = 9x-45.. although in this case. since there isn't a bracket around 13-4. you'd multiply by the -4 first, giving you, 4x-20+30 =4x-10
If 
, then by rationalizing the denominator we can rewrite
Now,
and
