Answer:
Step-by-step explanation:
(a) Option B cost less at 120 miles driven
The cost difference at 120 miles between option A and option B is $15
(b) Option A and B cost the same at driving 60 miles.
Option B would cost more if you drive less than 60 miles.
<u>Part a)</u>
Given the expression

Apply exponent rule: 
∵ 
Rewrite 81 as 3 · 27
Rewrite 54 as 2 · 27

Factor out the common term: 27m³n
Therefore,

<u>Part B)</u>
Given the expression

Apply exponent rule: 

Rewrite as

Factor out common term 5y²x²z

Therefore,

Answer:
f(x)= x^3
Step-by-step explanation:
4m + 3m + m. Add it all.
= 7m