Please assist on this problem

  a) linear. Cost per minute is a constant.

  b) f(x) = 40 -0.15x

  d) f(100) = 25. The remaining value is $25 after using 100 minutes.

Step-by-step explanation:

a) Since the cost per minute is a constant, the remaining dollar value of the phone decreases by the same amount for each minute used. The cost as a function of minutes used is a linear function with a constant rate of change.

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b) The value starts at $40 and decreases by $0.15 for each increment of x (minutes used). The function can be written as ...

  f(x) = 40 -0.15x

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d) Put 100 where x is in the function definition and do the arithmetic.

  f(100) = 40 -0.15×100 = 40 -15

  f(100) = 25

According to the variable and function definitions, x=100 means 100 minutes have been used; f(x) = 25 means the remaining value of the phone is 25 dollars.

  f(100) = 25 means the phone's remaining value is $25 when 100 minutes have been used.

the answer is c

hope this !

i dont know sorry

step-by-step explanation: