This is a slightly challenging problem from Dan Griller.
“Every pupil at the Euler Academy studies French or Spanish. At the start of the year, one third of the French students also studied Spanish, and 2 fifths of the Spanish students also studied French. After one term, six of the double-linguists dropped French, so that now only a quarter of the French students study Spanish. How many pupils are at the Euler Academy?”
Just to be clear, “French students” means Euler Academy pupils studying French, and similarly for “Spanish students.”
See the Language Students Puzzle for solution.
Since the changes in Twitter (now X), I have not been able to see the posts, not being a subscriber. But I noticed poking around that some twitter accounts were still viewable. However, like some demented aging octogenarian they had lost track of time, that is, instead of being sorted with the most recent post first, they showed a random scattering of posts from different times. So a current post could be right next to one several years ago. That is what I discovered with the now defunct MathsMonday site. I found a 
This essay is slightly tangential to my usual fare, but it is prompted by a most amazing video that convinced me that the impact of AI this time is not hype, but rather a real threat to our society. I found the 
This is another puzzle from the Maths Masters team, Burkard Polster (aka Mathologer) and Marty Ross as part of their “Summer Quizzes” offerings.
Another 
A prevalent theme of much of popular mathematical exposition and debates about mathematics education concerns how to interest a wider population in matters mathematical. For the most part I feel that essays that try to present the “beauty” of mathematics are doomed to failure, as are most discussions of esthetics. The underlying goal of such writing is a legitimate and laudable attempt to show the appeal of math. But I fear it succeeds only with those already converted. So is there another way?
After a hiatus of four years, Stephen Welch is back with some timely videos at 
This is a problem from the 1987 American Invitational Mathematics Exam (AIME).
This is the second part of the problem from Raymond Smullyan in the “Brain Bogglers” section of the 1996 Discover magazine.
