Why this code doesn't work?

Question

while True:
print ("welcome\ntype add, subtract, divide or multiply")
z = input(": ")
if z == "add":
print ("enter first number")
x = float(input(": "))
print ("enter second number")
y = float(input(": "))
print (x+y)
elif z == subtract:
print ("enter first number")
x = float(input(": "))
print ("enter second number")
y = float(input(": "))
print (x-y)
elif z == divide:
print ("enter first number")
x = float(input(": "))
print ("enter second number")
y = float(input(": "))
print (x/y)
elif z == multiply:
print ("enter first number")
x = float(input(": "))
print ("enter second number")
y = float(input(": "))
print (x*y)
else:
print ("invalid input")

Answer 1

Okay, thank you very much.

Answer 2

Thank you. I wrote add 1 2 in different lines during input and it gave me 3.0. But at the end there was an Eof error for line 3. What is eof error?

Answer 3

So the code is alright? Is it just sololearn limitations?