Prove that for wff a, b of the system l, if {a) l в, then (a → b) is a tautology you can use theorems from class, if you reference them properly.

The awnser is d. i just looked it up 

Function tipcalculate (slider, bill){  var tip = document.getelementbyid('tipamount');   var slideval = document.getelementbyid('slideval');   var bill = document.getelementbyid(bill).value;   var prcnt = slider * .01;       if (bill == null || bill == '') {      tip.innerhtml = ' enter an amount';       return false;   }  if(isnan(bill)) {      tip.innerhtml = ' enter a number';       return false;   }  if(bill > = 0){      tip.innerhtml = '$' + (bill * prcnt) .tofixed(2);   slideval.innerhtml = slider + '%';   }}

Ithink it's b. not sure though.

As a network administrator, you must create an active directory account for the computer using djoin/provision command. i feel there is more missing in this question that was inquired