Automobile service invoice (Python 3)

4.10 Program: Automobile service invoice (Python 3)

(4) Extend the program to allow the user to enter a dash (-), which indicates no service. (3 pts) 


Select first service: Tire rotation

Select second service: -

Davy's auto shop invoice

Service 1: Tire rotation, $19
Service 2: No service

Total: $19

Here is my code:

# make a dictionary for Davy’s auto shop

davy_auto_services = {

  ‘Oil change’: 35,

  ‘Tire rotation’: 19,

  ‘Car wash’: 7,

  ‘Car wax’: 12


print(“Davy’s auto shop services”)

for key, value in davy_auto_services.items():

  print(key, ‘– $’ + str(value))


first_service = input(‘Select first service: n’)


second_service = input(‘Select second service: n’)


print(“nDavy’s auto shop invoicen”)

#make if statement to loop 

if first_service in davy_auto_services:

  print(‘Service 1:’, first_service + ‘, $’ + str(davy_auto_services[first_service]))


  print(‘Service1: No service’)

#make if statement for sevice 2  

if second_service in davy_auto_services:

  print(‘Service 2:’, second_service + ‘, $’ + str(davy_auto_services[second_service]))     


  print(‘Service 2: No service’)


total = davy_auto_services.get(first_service) + davy_auto_services.get(second_service)

print(‘Total: $’+ str(total))

#t = 0

#if first_service == “No service”:

  #print(‘Total: $’ + str(t))

#elif second_service not in davy_auto_services:

  #print(‘Total: $’ + str(second_service_total))

Here is the error I get:

Traceback (most recent call last):

File “”, line 31, in <module>

total = davy_auto_services.get(first_service) + davy_auto_services.get(second_service)

TypeError: unsupported operand type(s) for +: ‘int’ and ‘NoneType’

All the other code works fine except for the very last piece. I have no idea how to print only one price..

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