Let $k = the monthly base fee.
The variable cost is $0.30 per minute.
Let
C = total cost in a month
x = minutes used
September:
x = 120 minutes
C = $50
Therefore
k + (0.30)(120) = 50
k + 36 = 50
k = $14
October:
x = 165 minutes
The cost is
C = 14 + (0.3)(165)
C = $63.5
Answer: $63.50
The zeros of the function is r=6, -10
Its 3.000+400+5 that's your answer
