What is wrong with if else statement in my Python code

I'm trying to do follow python code.. but every time I try, There is an error. they said Syntax error..(elif).How i figure this out.Or is there any wrong with my write function...?

file = open("text.txt","a")
n=0
while n<=5:
 y = str(input("name: "))
 x = int(input("marks: "))
 result = "Pass"
 if x<35:
    result = "Fail"
    print(y,result)
 file.write('"{}#{}"/n', format(y,result))
 elif 35<=x<=54:
    result = "S"
    print(y,result)
 file.write('"{}#{}"/n', format(y,result))
 elif 55<=x<=64:
    result = "C"
    print(y,result)
 file.write('"{}#{}"/n', format(y,result))
 elif 65<=x<=74:
    result = "B"
    print(y,result)
 file.write('"{}#{}"/n', format(y,result))
 elif (75<=x<=100):
    result = "A"
    print(y,result)
 file.write('"{}#{}"/n', format(y,result))
 else:
    print ("Invalid Enter")
 n = n+1
file.close