IN PHP language

how can i make my function named "add add two numbers together and make it able to handle negative numbers?

how can i make subtract function name "subtract" like my "add" function(while loop and succe)

it must be able to handle negative numbers

multiplication function

named "mult"

must handle negative numbers

use the same algorithm from "add" (while loop and suc)

make a exponential function

named "exponential"

only handle positive exponents, but handle negative bases.

must use the same algorithm from above

--- must be able to properly run the code at the bottom of the picture

function successor($num) { return $numre1; function add($n, $k) { $1=0; while($i