Simple Calculator

--[[Calculator]]--
os.loadAPI("apis/cl")
term.clear()
term.setCursorPos(1,1)
print("RobustCreepers Calculator Version 2.0")
print("Do you want the calculator to repeat? y/n")
answer = read()
if answer == "y" then
while true do
  print("Do you want to add, subtract, multiply, or divide?")
  op = read()
  print("What is the first number to be operated on?")
  num1 = read()
  print("What is the second number?")
  num2 = read()
  if op == "add" then
   textutils.slowPrint("Adding....")
   sleep(1)
   term.clear()
   term.setCursorPos(1,1)
   ans = num1 + num2
   print("Answer is "..ans)
   sleep(2)
  else
  end
  if op == "subtract" then
   textutils.slowPrint("Subtracting....")
   sleep(1)
   term.clear()
   term.setCursorPos(1,1)
   ans = num1 - num2
   print("Answer is "..ans)
   sleep(2)
  else
  end
  if op == "multiply" then
   textutils.slowPrint("Multipling....")
   sleep(1)
   term.clear()
   term.setCursorPos(1,1)
   ans = num1 * num2
   print("Answer is "..ans)
   sleep(2)
  else
  end
  if op == "divide" then
   textutils.slowPrint("Dividing....")
   sleep(1)
   term.clear()
   term.setCursorPos(1,1)
   ans = num1 / num2
   print("Answer is "..ans)
   sleep(2)
  else
  end
end
else
print("Do you want to add, subtract, multiply or divide?")
op = read()
print("What is the first number to be operated on?")
num1 = read()
print("What is the second number?")
num2 = read()
if op == "add" then
  textutils.slowPrint("Adding....")
  sleep(1)
  term.clear()
  term.setCursorPos(1,1)
  ans = num1 + num2
  print("Answer is "..ans)
  sleep(2)
else
end
if op == "subtract" then
  textutils.slowPrint("Subtracting....")
  sleep(1)
  term.clear()
  term.setCursorPos(1,1)
  ans = num1 - num2
  print("Answer is "..ans)
  sleep(2)
else
end
if op == "multiply" then
  textutils.slowPrint("Multipling....")
  sleep(1)
  term.clear()
  term.setCursorPos(1,1)
  ans = num1 * num2
  print("Answer is "..ans)
  sleep(2)
else
end
if op == "divide" then
  textutils.slowPrint("Dividing....")
  sleep(1)
  term.clear()
  term.setCursorPos(1,1)
  ans = num1 / num2
  print("Answer is "..ans)
  sleep(2)
else
end
end