How can you get user input on this code?

Question

https://code.sololearn.com/WEYSPPQh33Zo/?ref=app

Answer 1

Ok and {Hello plus name}

Answer 2

I mean, the last one

Answer 3

https://code.sololearn.com/W16u0u6q0y58/?ref=app

Answer 4

How can I add math to prompt()?