okay i get it, thank you for helping , and my answer this:
var processed;
function processArg(num) {
return (num +3)/5;
}
processed = processArg(7);
/*its value of into the brackets Assigned to num in the function process then num + 3 / 5 = 2 and this value assigned to processed.
my english is not so good but i hope i telling that i understood */