Dear Amy: I am the mother of a 21-year-old girl and an 18-year-old boy. My problem is with my daughter. She treats me very disrespectfully. She’ll tell me to “shut up” and calls me “stupid” or “dumb” if something doesn’t suit her or if she’s feeling stressed about school or work (she is a straight-A student working a summer internship with a major accounting firm).

When I try to address the behavior, she’ll shut me down by mocking me.

Here is an example: Yesterday morning she came into my bedroom (on the main floor), angry at me for turning off the air conditioner. Her room is on the second floor and she said she was too hot to sleep all night. I explained that it was 60 degrees outside and we didn’t need the air conditioner. She said, “You’re so dumb; hot air rises what are you — stupid?”

My son doesn’t treat me this way and is very respectful and kind. How can two kids from the same family be so different? My husband says I should completely ignore her and not do a thing for her — basically alienate her. This approach doesn’t feel right. What do you think?

— Frustrated Mom

Dear Mom: Your daughter seems to single you out for this disrespect, but you and your husband should present a united front in dealing with it. You should be in basic agreement about what you will — and won’t — tolerate from your little miss bossy pants, otherwise she doesn’t have much incentive to change.

You three should meet privately to discuss her behavior. Ask her if she talks to her professors, mentors or co-workers this way. Then ask her why she talks to you this way. Listen to her answer; if she doesn’t answer or shrugs this off, then let some uncomfortable silence hang in the room.

Tell her that she needs to behave differently. Don’t offer ultimatums (she’ll be forced to wonder about the possible consequences).

If this continues, then I agree with your husband — ignore her and do nothing for her until she figures out how to get back into her parents’ good graces. If her behavior deteriorates, the next step might be to tell her that she needs to find somewhere else to stay. Be calm, firm, in-charge and — when the time comes — forgiving. She’s young and testing you.

Dear Amy: I’m sure you’ve been asked this many times in the past, but I need to know — if you’re dating someone, is it the man’s responsibility to pay the tab all the time?

And if I were to approach my girlfriend about this issue, what is the best way to go about it?

— Moneybags

Dear Moneybags: Yes, this is a perennial issue between dating couples. The question is raised, again and again, because as time goes on, social mores change as we all make the transition away from some traditions and toward others.

Every couple needs to discuss money at some point, and the sooner you do this, the better.

You could start this conversation with your girlfriend by asking her if she thinks the man should always pick up the tab, and if so — why.

My own view is that whoever has more should give more. The person with fewer assets can express her own generosity by finding ways to host inexpensive outings. In the healthiest relationships, the overall attitude is one of balanced sharing, appreciation and gratitude.

Dear Amy: I am writing in response to readers regarding hiring a contractor with a Trump bumper sticker on his truck. In another time and in another political atmosphere, I would have no problem with this. However, Trump represents everything that is wrong with America: greed, racism, inequality and class war. To me, this is the same as voicing support for the KKK, confederate flag and other hate-inspired groups. Advising your readers to stick their heads in the sand and suppress their moral indignation was very disappointing. Posting political messages on your business vehicle is certainly a “right,” but it’s also stupid, as it will alienate some customers and you’ll lose business. Amy, you should be ashamed of yourself.

— A Disappointed Reader

Dear Disappointed: I’m sorry to have disappointed you, but advising mutual respect and tolerance is hardly something to be ashamed of.