Most “graduates” of the city’s public schools lack the skills to prosper in college or the workplace, but at least business is booming for the United Federation of Teachers.

As Carl Campanile reported in Monday’s Post, the city teachers union is spending more furiously than a drunken sailor: In the year ending last June 30, the UFT upped outlays by $13 million over the year before, to $182.1 million. That equals the entire budget for the city of Albany.

It helped that the union collected an extra $7 million in dues (to $151 million total), thanks to 7,000 new teachers hired under Mayor de Blasio’s Universal Pre-K program.

UFT boss Michael Mulgrew’s smug justification for it all? “Defending public education is increasingly expensive.”

Starting with his pay: The former middle-school shop teacher gets $283,804 — more than Mayor de Blasio, and $56,000 more than Schools Chancellor Carmen Fariña.

Heck, six UFT staffers out-earn Fariña, who runs de Blasio’s $24 billion, 1 million-student Department of Education. Another 65 staffers pull down more than $150,000.

The UFT also spent $3 million on catered meals, and more for baseball tickets and for junkets to Orlando, New Orleans and Vegas.

To be fair, the union also helps its outside friends, handing $3 million to various community and advocacy groups.

And it ponied up $125,000 for de Blasio’s nonprofit, United for Affordable NYC. No, the mayor’s housing agenda has nothing to do with education — but pleasing de Blasio is vital to the UFT’s real work, which is preserving its members’ privileges.

Ironically, news of the union’s spending boom follows fresh word of the failure of the mayor’s UFT-friendly Renewal program, which was supposed to turn around dozens of failing city public schools.

Thanks to plummeting enrollment and/or still-stagnant scores, Fariña is closing another six Renewal schools, and merging three others with less-dysfunctional schools with which they share buildings.

In all, the chancellor is closing or merging 22 failing schools, a tacit retreat from de Blasio’s bluster, back when he started the Renewal farce, that “we reject the notion of giving up on any of our schools.”

No apologies yet from City Hall to the kids stuck attending these schools in the years before the de Blasio-Fariña-Mulgrew regime finally stopped pretending.