Answer:
13
Step-by-step explanation:
You are given the function

To find the value of the function f(x) at point x=a, you have to substitute a instead of x into the function expression.
In your case, you have to evaluate f(x) when x=10. Substitute 10 instead of x into the function expression:

Answer:
7n = 12+ 3n
Step-by-step explanation:
The first thing to do is subtract 3n from 7n. This would get you 4n = 12. 4 times 3 equals 12, so n equals 3.
To check your answer. 21 = 12+9. sure enough it matches our answer
I believe 1/3 since there is three of them.
But don't take my full word for it.
I’m pretty sure you do need to subtract 30-8.