Well, if you need to solve for f, then..
b-2f=2f-2f+6
b-2f=6
b-b-2f=6-b
-2f=6-b
-2f÷-2=6÷-2-b÷-2
f=-3-1/2b
Given:
The expression is

To find:
The constants in the given expression.
Solution:
Terms can be a number, variable and product of both. these are separated by "+" sign.
Variables terms: These terms contains at least one variable.
Constant terms: These terms are free from the variables. it means there are no variable.
We have,

In this expression, the terms are 6x, -8, 4y, 5, variable terms are 6x, 4y and constant terms are -8, 5.
Therefore, the last option is correct, i.e., -8, 5.
Example:
5/20 x 100 you put whatever fraction your looking for into calculator and multiply by 100
Answer:
7.5
Step-by-step explanation: She can run 5km in 30 mins. That means she can run 1 km every 6 mins. 45/6= 7.5. She can run 7.5 km in 45 mins. Such an amazing feat my chubbiness can't compete with.