Plz help 20 points if you get it right and I will give you brainliest

The first one cannot be simplified

reason: usually when simplifying an expression you combine like terms but in the given expression there are no like terms

An example of like terms would be 6a and 9a

Essentially what i am saying is that the variables have to be the same in order for them to be combined

The second one is 36r

This is the answer because they tried to combine like terms that aren't similar

r and f are not the same variable therefore they cannot be combined

Hope this helps :)

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.