Parafost

Hey all, I have been trying to get into PHP for a while now and I have a question that if someone could explain to me I would really appreciate it. The code is as follows; $a = 57; $b = "$a + 3"; echo $b; $c = $a + 3; $d = 54; echo $c; Now I am aware that the answer to the first question would be 60. But, I am curious, without the " around $a + 3; will there be any change to the answer or will the answer still show as 60? if the use / no use of the " " could be explained I would really appreciate it. Thanks a lot Para