An email address contains the @ character. Write a program that takes asks for an email address input from the user and determines whether it is a valid address or not. This is based on the presence of the @ character and no spaces in the string. You do not need to worry about any other characters in the input word. Output the result "The word IS an email address" or "The word IS NOT an email address" Example - Input: [email protected] Output: The word IS an email address Input: my123user Output: The word IS NOT an email address Your code should include comments to describe the program logic and use proper indentation for readability.

a. $250

b. The total cost for x month is $200 + $50 × x

c. Please see the attached graph

d. Yes, there is a proportional relationship between time and the cost of the cell phone plan

e. $350

Step-by-step explanation:

The given parameters are;

The costs to start on the cell phone cell = $200

The charge each month = $50

a. The total cost to use the cell phone plan for 1 month = Start up fee + Monthly charge = $200 + $50 = $250

b. The total cost for x month, c = $200 + $50 × x

c. Please see the attached graph

d. Yes, there is a proportional relationship between time and the cost of the cell phone plan

e. The line parallel to the line graphed that goes to the point (0, 350), is given as follows;

y = m·x + c

Where;

m = 50

y - 350 = 50 × (x - 0)

y = 50·x + 350

The startup fee is given by the total cost at x = 0, when the monthly fee is excluded, which gives;

c = 50 × 0 + 350 = 350

The startup fee for the pricing plan = $350.