13-x = 13- x
theres is no answer for that x its a variable and 13 is a constant so is just 13-x
10 is your answer!! hope this helps
Answer: Choice A. 
Explanation:
The rule is that stuff of the form
becomes
where k is some positive number.
So we'll have these steps

In the third step, I subtracted 6 from all sides to isolate x.
The last step indicates we'll have open holes at -16 and 4, with shading in between. It visually tells the reader "x can be anything between -16 and 4, but can't be equal to either endpoint".
Answer:
C. 33.2%
Step-by-step explanation:
Number of trials n = 85
Probability of success p = 0.5
Number of successes r = 40
Use cumulative binomial probability:
P(x ≤ r) = binomcdf(n, p, r)
P(X ≤ 40) = binomcdf(85, 0,5, 40)
P(x ≤ 40) = 0.332
The answer is (root 6) - 6,
-(-root(6) + 6),
(Root 6)- 6