Question Completion:
See attached.
Answer:
Luwak Coffees
1. Water bill is fixed.  Electricity bill is variable.  Telephone bill is mixed.
2. High-Low method:
Water bill = $120 + 0q
Electricity bill = $0.3q
Telephone bill = $140 + $0.02q
where q = the quantity of each cost consumed.
3. Water bill = $120 + 0q
Electricity bill = $0.3q
Telephone bill = $140 + $0.02q
= $260 + $0.32q
4. No solution.  There is no relationship with machine hours, employees, and units with utility bills.
Explanation:
a) Data and Calculations:
Month           Electricity Bill    Kilowatt Hours Used
January            $ 720                       2,400        
February          $ 840                       2,800
March             $1,098                       3,660
April                  $ 810                       2,700 
May                 $1,176                       3,920
June               $1,248                       4,160 
July                $1,044                       3,480 
August           $1,194                       3,980 
September   $1,260                       4,200 
October        $1,230                       4,100 
November    $1,188                        3,960 
December  $1,266                        4,220 
Telephone Bill $184.
Low cost = Jan  $ 720                2,400
High cost = December  $1,266         4,220
High cost = December  $1,266         4,220
Low cost = Jan                $ 720         2,400
Difference =                     $546         1,820
Variable cost per unit = $546/1,820 = $0.3 per kwh
Fixed cost, using December's figures:
Variable cost = $1,266
Fixed cost = $0 ($1,266 - 4,220 * $0.3)
Telephone bill:
High, June $197.60     2,880
Low, April     178.20      1,960
Difference $18.40        920
Variable cost = $18.40/920 = $0.02
Fixed cost = Total cost - Variable cost
= $197.60 - (2,880 * $0.02)
= $140