Since 1/8 of his books are mystery and he has three of them, you would multiply 3 by 8 to find his total number of books which is 24.
You can find the remainder right away by simply plugging in

. The polynomial remainder theorem guarantees that the value of

is the remainder upon dividing

by

, but I digress...
Synthetic division yields
3 | 2 -11 18 -15
. | 6 -15 9
- - - - - - - - - - - - - - - - -
. | 2 -5 3 -6
which translates to

(and note that

, as expected)
Answer:
x=3
Step-by-step explanation:
Use pemdas!
First use distributive property to get rid of the parenthesis, by multiplying 2 by 3x and -4. Then combine like terms and use inverse operations to simplify each side until you get it down to just x! Hope this helped! :)
The format is y = mx + b
where y would be your C
x would be your M
m would be the price per mile (2.20)
and b would be your initial fee (2.75)
put this together in that format and we get
C = 2.20M + 2.75