JavaScript number variables

Question

Hello, everyone. I need help understanding this operation:

var a = "8";
var b = a + 3 - a;

document.write(c); //output is 75

Why is 75? I thought that numbers in quotes were treated as strings when they came with a plus sign. Shouldn't it be 85?

This is eating my head; I can't see the logic behind this :S

Thanks in advance for your help.

Answer 1

b = "8" + 3 - "8"
b = "83" - "8"
b = 83 - 8
b = 75

Special condition, + also use as concatenation of string if the first var is string follow by a number.

Answer 2

Oh! I see it now. Thank you, Calvin :D

Answer 3

helped me too thanks for that

Answer 4

according to calvin it is 75, some people make the mistake of writing "8"+"3" is 11 but, you join them together to be 83 then i subtraction situations, you minus it by3 which gives you 73 as an answer its easy hope you understand?