To solve this equation, plug your input value into the function to find your output.
This would leave you with:
f(4)=4+21
Add the two integers together:
f(4)=25
So he output value of that function with he input of 4 would be 25.
You have to calculate the probability that it lands on 4. There are 2 possibilities from the 8 that it lands on 4. So the chance is 2/8, which is the same as 4/16
The answer is B-Associative Property