[ SmokeDetector ] Few unique characters in answer: What is the difference between the normal average and weighted average? by Kop on math.stackexchange.com …

Would it be useful to collect somewhere posts flagged as spam which SD did not notice? (With intention to help SD to learn.)

[ SmokeDetector ] Link at end of answer: If $f(x,y)$ is a function that its contour lines are straight, is it necessary looks like $f(x,y) = ax + by + c$ by Mukesh Negi on math.stackexchange.com …