This is a Valentine’s Day puzzle from BL’s (Barry Leung) Math Games.
“Happy Valentine’s Day everyone, I hope you are having a euphoric moment, but if not, you can try this algebra puzzle about maximizing the expression LUV + LU + UV + LV given L + U + V = 12, where L, U, V are non-negative integers.”
See Maximizing Love for a solution.

This is another
This
This is an old puzzle from Catriona Agg that I found on BL’s Math Games
This is a slightly challenging
Here is a probability
Here is another
This is another
This is an interesting algebra