Answer 1

Wrap your prompt() call in
parseInt( ) or parseFloat( ),
depending on what type of number you expect.

parseInt():
https://www.geeksforgeeks.org/javascript-parseint-with-examples/

parseFloat():
https://www.geeksforgeeks.org/javascript-parsefloat-with-examples/

Answer 2

You should enclose the term
250 - healthSelect
in braces. The reason for this is that you perform string addition - since prompt() takes in a string as its argument - and the '-' operator is not specified for such a task.
However, if you wrap the term in braces, it will be considered as integer subtraction, and afterwards the result will be added to the string before it.

Answer 3

https://code.sololearn.com/WUO1bV5B7v5O/?ref=app