This is about If Else Statement, How do I fix this?

Question

Hello, I created a code but I don't know where's the error.
When I input "no" it still proceeds to the question under Yes here's the code:

y_n = (input("I want you to answer two simple math equations \nand you only have 1 attempt. \nAre you ready? "))
if y_n == "yes" or "Yes" or "YES":
print ("Let's continue...")

first = (input("1. 18÷3-7+2*5 = "))

if int(first) == int(18 / 3 - 7 + 2 * 5) :
print("Good. Next...")
else:
print("Wrong. Go back to preschool.")

second = (input("2. 6*4÷12+72÷8-9 = "))

if int(second) == int(6 * 4 / 12 + 72 / 8 - 9):
print("Perfect. You can be the President of the Ph.")
else:
print("Wrong.")

elif y_n == "no" or "No" or "NO":
print("Ok, go back to kinder.")

THANK YOU SO MUCH

Answer 1

taking the hint from Ipang , we can also simplify the code a bit:

insert a line of code that converts the input string to lower case directly after the input() line.

then:
...
if y_n == "yes":# now we need to check only against lower case answers like "yes" or like "no"

Answer 2

Use `in` operator to check whether <y_n> was in some predefined string instead.

if y_n in "yesYesYES":
# code
else:
# assume input was "No"

Answer 3

Also, note that you're using 'or' in the wrong way.
if y_n == "yes" or "Yes"... Tests if y_n equals "yes", then tests "Yes". A non-empty string evaluates to True, so this will always be true.
If you want to compare a variable with multiple values, use:
if variable in (value, value, value...):
If doing more complex comparisons, write each one. For example:
if x > 0 and x < 10: