Math Puzzle Solved with Python

This is a question in a elementary school math text.  The problem is stated in the first 5 comments. Whatever you input for the 2 days, the answer is always 21.

# Mrs. Simpson waters her geraniums once every 3 days, and she waters her other house plants once a week.

# How often does Mrs. Simpson water all the plants on the same day?

# Geraniums are watered once every 3 days i.e. if watered on Monday, then watered again on Thursday.

# Other plants are watered only once a week.

# We have to determine how many days it takes for the watering days to be the same day.

# Best way to do this is to first wait for the day to match, then count the number of days until the next #matching day. Otherwise, we get different answers for different geranium watering days. 

# Ask for the first day that geraniums are watered.

spelling_indicator1 = 0

while spelling_indicator1 == 0:

     germ_first = input('What is the first day that the geraniums are watered (enter at least first 2 letters)? ').lower()

     # grab the first 2 letters of answer

      germ = germ_first[0:2]

     if germ not in ['su','mo','tu','we','th','fr', 'sa']:

         spelling_indicator1 = 0

         print('Spelling error, try again.')

     else:

         spelling_indicator1 = 2

# ask for the day of the week the other flowers are watered

spelling_indicator2 = 0

while spelling_indicator2 == 0:

      # grab the day of week that other flowers are watered

      others_first = input('What is day that other flowers are watered (enter at least first 2 letters)? ').lower()

      #grab the first 2 letters of answer

      others = others_first[0:2]

      if others not in ['su','mo','tu','we','th','fr', 'sa']:

         spelling_indicator2 = 0

         print('Spelling error, try again.')

     else:

         spelling_indicator2 = 2

no_of_days = 0

match_counter = 0

while match_counter < 2:

    if germ == others:

        match_counter = match_counter + 1

        if match_counter != 2:

            no_of_days = 0

        if match_counter == 2:

            break

     if germ == 'su':

        germ = 'we'

    elif germ == 'mo':

        germ = 'th'

    elif germ == 'tu':

        germ = 'fr'

    elif germ == 'we':

        germ = 'sa'

    elif germ == 'th':

        germ = 'su'

    elif germ == 'fr':

        germ = 'mo'

    elif germ == 'sa':

        germ = 'tu'

    no_of_days = no_of_days + 3  #this line is in the while loop

print('The number of days between matching watering days is: ', no_of_days)

Click on the image below to expand it and see the results of running the code twice.