How use a previous out value from a function in the next code

Question

Imagine this:
function op(o,p) {alert(p*o)} ts(5,6);
How can I use the answer I get from the function above to write a new code.

Answer 1

Function name(a,b){
var c = a*b ;
return c ;
}
var d =5*name(4,5) ;

// var d = 100 ;

Answer 2

Return what you want and save it in a variable

Answer 3

How?