At a construction site, Jorge is in charge of hiring skilled workers for the project. Out of 80 candidates that he interviewed, he found that
45 of them were painters;
50 of them were electricians ;
50 of them were plumbers;
15 of them had skills in all three areas;
all of them had skills in at least one of these areas.
If he hired everyone who were skilled in exactly 2 areas, how many candidates were hired?