Someone Help me fix the error

Question

print("calculation of total cost after discount")
n = input("enter the cost")
a = int(n)
answer=0.9*a
print("the final cost is", answer)

Answer 1

The right way to input n is
n=eval(input("enter the cost:"))
where eval get your input

Answer 2

?? Can't see an error exactly but here how I would write the code;-

print("calculation of total cost after discount")
n = int(input("enter the cost:-"))
answer = 0.9 * n # this give you 10% discount.
# or answer = n - (0.9 * n) if the 0.9 is the discount
# (90%).
print(answer)